Can my sister and mom build a bridge after decades of miscommunication before my parents move closer to them?

Hi Folks! Long time listener, first time poster. I'd love some advice on how my mom and sister can rebuild their relationship. There's a lot of context so it's hard to fit it all into one post, but I love both of them and just at a loss of how they can overcome their issues after years of not being able to communicate with each other before they end up losing each other.

For some context, my mom and sister used to be very close. My mom is a great mom, and I think she deserves the world. One of her main sources of pain in her life was that she left her home state and moved for work, where she met my dad. She never moved back home and she's always missed her family and wanted to have her community. She is so kind and full of love, that she was called mom at her old job before she retired. However, she's also very sensitive. If we said something that she didn't like or found hurtful, she would give us the cold treatment and not speak to us until either we apologized or she got over it. She was always good at a guilt trip, but I think now, she's trying to have healthier habits. To be fair, she also did a lot of heavy lifting in our childhood and was always involved, with not a lot of recognition or appreciation. As an adult, I try my best to make sure she knows how loved she is and we have a great relationship, My sister is really intelligent, like genius level, and a little socially awkward- she's gifted but never been diagnosed with anything. Growing up, she and my mom were really close and when she left for college, they would still talk almost daily. We were a little nervous that she wouldn't branch out. In high school, she met her now husband, and they've been together since. He really brought her out of her shell and they've been really good for each other. Now, he's a great dad to the girls. We used to be closer when we were all in school, but now I feel like I barely know him. I think he does a great job of supporting my sister, but it feels a bit like he doesn't like my mom anymore. My family has always supported them and in college, my parents even let him stay with them for a semester while he was trying to finish his degree and needed to be closer to his internship.

The issue started when my sister and her husband moved farther from home and had to plan their return trips. They always ended up staying with her husband's family and my mom felt it was an unfair split. From what it sounds like, his family has more organized family hang outs while our family is more casual let's hang out, so it skewed more towards his family. My dad has always tried to be neutral, but support both sides. He would try to say it's her family and she needs to prioritize their unit of 2, which is now 4 and has always supported them, while also reassuring my mom. This kind of back and forth has been happening for about 15 years now. The resentment on both sides have grown and they just don't know how to communicate. Any time they try to have a conversation, my sister doesn't hear my mom, and my mom gets hurt and they both end up in tears. They can never reach a resolution and it's severely impacted their relationship. Another thing is, my parent's love language is they love to help people. They'll always be there if we need, and when we've had emergencies over the years, we've never had to worry that we won't have support and we're very lucky in that sense.

The thing where this is causing issue, is for my sister and her husband, they see it as overstepping. They are very independent and like to have control over their slice of life, which is understandable, but if my parents want to come help, they're incredibly particular about how they can interact in their lives. For example, when they first moved to their house, my parents were ready to come help with any renovations, but to my sister and her husband, they were stepping in where help wasn't needed or wanted, which hurt my parent's feelings. Since then, they've had 2 amazing kiddos, and while we thought this may help bridge the gap, this has led to new issues between them. My sister and her husband are very particular about how they raise their kids, which we all agree is their right. They're wonderful parents, and just want to make sure no plastics or anything inorganic makes it into their system. However, they don't trust my parents to follow their guidelines, even though my parents have been working hard to make sure they can follow their boundaries and still have a relationship with them and their grandkids. My sister and her husband seem to think the worst of my parents, which I don't think is fair. They are trying their best, and I feel like she's always quick to jump to them being unreasonable.

This winter, I went home for the holidays and did a fun trip to see family. I was with my parents for most of the time and had a great time with them both, and didn't have any issues. I mostly speak with my mom, but wanted to hear where my sister was coming from. She was saying she doesn't want so much help because she really likes everything she's been doing. While she's stretched thin, she really enjoys her life and this is the main point of stress. My sister's told me all would be resolved if she stopped with the guilt trips. I was like that's a great point and I totally get it. Another important thing to note for this was that she had sent my parents a list of what to get the girls for Christmas. My mom got what was on the list and 2-3 small things that were off the list (I think a couple outfits and a toy or two). My sister did not like that (I'll come back to this). During the holidays is also my mom's milestone birthday came around and I planned everything based on what she enjoys since Lizzie was busy. Since my sister and her husband couldn't be there on the day, we wanted to do a local celebration while we were in town. When we went for lunch, my sister was late and in a grumpy mood. Not very long into it, she told my mom that they would be returning the additional gifts and that they should have just stuck to the list. I have to say the way it was delivered would have hurt my feelings too. My mom was hurt by this and it led to drama and incredible tension the rest of the day and the birthday plans were ruined. I don't think she should have lied about it, but also time and place and also delivery. You don't have to be so honest on an important day. Anyways, that apparently was my sister's last straw, where she said we need to go to family therapy or you guys can't move here in the future. They ended up going to one together and it sounds like it helped a bit, but only one isn't the most helpful.

The current situation is, both of my parents are wanting to move and be closer to my sister. My mom has been wanting to leave the area we grew up in for some time and with them both retiring, they want to have a new scene and also be close to the grandkids and family. My sister and her husband are in another state, so my parents have been traveling a lot to come see them. My brother in law's family doesn't like to travel to see them so when they come visit, they stay with his family. It makes sense in terms of time split, but also feels like my parent's have been doing so much for them, but they only get to see them if they come out and spend a bunch of money to get there. We're hoping if they move closer, this could help with some of these original issues where time is split up since they'll just be able to be there without the lift of driving 6 hours each way and spending money on a hotel (my sister and her husband put a cap that they can only stay at their house for 2 nights or else they need to get a hotel). The four of them had a talk and said they could move out, but wanted to set boundaries. It's healthy to set boundaries, but they said they won't help with any of the house searching and that they didn't want to see them all the time, but nothing like we're happy to have you guys here so I think they were a bit bummed, but still want to move bc it's in the middle of both sides of their family and they want to travel and explore a new spot. My sister is worried they'll try to insert themselves into every part of their life and that the worlds will collide and that they'll be dependent on them for any sort of integration into the community. It's a fair concern but at this point, the pendulum has swung in the complete other direction and they are just not willing to help them with anything or be happy about any sort of interaction with them.

My parents met with a realtor and they said May/June was the best time to sell and they also found a house really quickly and are so excited to be out there. I recently called my sister and she said her husband is FURIOUS that they're moving there so quickly and she's also pissed. They bought a bigger house and they were like oh it's because they want to have the girls over all the time. Like no, if you talked to them, you'd know they got it because the other houses in the area at the same price were not great quality and this one had a pool. They are also looking into volunteering opportunities in the area and want to join clubs and sports. They're building a life nearby, but they won't be in their hair all the time They just always jump to the worst. I understand where they're coming from, but I wish they would just let themselves enjoy my parents, because they're actually amazing people.

To give some context for myself since it's important as I tell this story, I have my own biases, which may be clouding this. Growing up, we were both really close to our parents and for me, I'm a bit more conversational and if we every had a disagreement, I was like let's figure this out right now and as an adult, it's become a lot easier. I've also been to therapy and I know it's not my job to regulate other people's emotions and try to set boundaries, but it's hard when it's two of your favorite people and they just can't figure it out. I am also in a very similar situation to my mom, where I live out of country now with my husband, and feel the sting of living so far away from my friends and family in the US. I don't have the same resentment my mom had, but I'd give anything to have them live near me and feel like I'm projecting my own feelings onto this, so can't give an unbiased view. This has also been going on for so long that there is for sure context that I don't remember or don't know about.

There hasn't been any egregious behavior on either side that I'm aware of, just miscommunication and build up unresolved issues. Nothing that would cause no contact. I'm sure I'm missing something, but when I speak to them both, they both make sense, but just can't get over their own built up issues. I think both sides make sense, but there is no clear way to bridge this gap. I know it's not my job to fix it, but I'd love to hear if anyone has an idea on how we can resolve this. I'm at a loss. Thank you for your help and thoughts!