I manage my aging parents’ finances and I’m about to start my own family soon. How do people keep things organized?

I’m 26 and I’ve been helping out with my parents' financial organization. For context my dad had me in his late 40s so he’s up there in terms of age. 

Growing up he was the one handling the household finances and organization such as storing important documents, paying important bills and debts.

My mom took care of us and he took care of her and everything else and that's always worked for them.

For the last 3 years or so I've been helping out, not financially because the old man earns a great pension, but just making sure everything is organized and paid on time. 

My dad missed a couple bills he could have easily paid which ended up in me having to talk to the companies, show their previous proof of payments and promise it wouldn’t happen again. 

I even found that one of his older subscriptions was overcharging him and I spent 4 hours in his archives (boxes on boxes on boxes in his attic), looking for the contract before I was able to get them out of it.

Since then I started tracking all of my parents' bills in a spreadsheet and going through it with them calmly every month so as not to stress out my dad. At first there was a little push back but he quickly realized that he needed my help since he kept forgetting the little things. 

Now before anyone points it out, yes I've been pushing to set up an automated payment system for him, but the old man is stubborn and says he likes to manually pay because it makes him feel in control of his money. 

I’m not gonna argue with him about it again because I sort of get it and I'm here to make his life easier, not try and change habits he’s internalized for over 70 years. 

The problem is I also manage my own household, and my girlfriend and I are getting married next year. She wants to try for a baby soon after and she’s more of the pays bills on vibes type of girl.

I’m the hard planning spreadsheets guy so I imagine I'm going to be the primary for this type of stuff. And honestly I don’t mind.

But with starting my own family and helping out my parents I need a proper system in place so documents (like contracts) don’t get lost and bills don’t go unpaid for both households.

Because even though I don’t mind the burden of managing two families, it is definitely gonna get to me eventually.

I keep looking for something that pulls it all together in one place. Not a budgeting app, not a bank. Just somewhere to manage the actual admin of running a household. Documents, bills, debts, all of it.

If possible letting my dad feel in control while managing everything would be great, though at this point I just want something that’s clean and simple to manage.

So my questions are:

1. Has anyone else experienced this before and how have they managed?
2. Does something like what i’m describing exist or is everyone just duct-taping their own system together? 
3. And if that’s the case, does anyone have a good system that I could put in place now before it all becomes really stressful?

Thanks for the help guys!