Planning for a month of visitors

Could people share their easy, quick to prepare or easy to pre-prepare, meals that go a long way...?

My MIL and BIL are visiting for a month in a couple of weeks time, and I'm getting a bit stressed about how to cater for them without bankrupting us, or spending hours in the kitchen. We'll essentially be 6 adults for a month - the two in-laws, husband, me, 2 teenage daughters.

I'm a decent cook. Can do the basics and follow more complex recipes. I'm also pretty good at improvising from what's in the cupboard. But that's not how I like to cater for guests. And I will admit to being in a bit of a cooking rut at the moment, with a lot of buying pre-prepared ingredients, deli type meals and far too many appearances of spaghetti bolognese.

Its a long time since they have stayed with us (they live literally on the other side of the world), and they have never stayed so long before.

Husband will help out as much as he can, but cooking isn't his strong point, and he's likely to default to barbecues or takeaways. I have asked him to check in with his family on what they particularly like to eat. The answer I have got back is "oh, anything is fine",which isn't hugely helpful.

Added complications:

• I work full time, sometimes at home, sometimes over an hour away.
• One daughter can't eat dairy, so any dairy heavy meals will need me to improvise an alternative for her
• Other daughter has some sensory issues with meat, so we do tend to avoid things like chops/steaks, but like her sister she'll happily take an improvised alternative (she has been known to happily have veggie sausages when we have steak, or pick the chicken out of enchiladas)
• the usual bit about us all trying to eat a bit healthier while providing enough fuel for sporty teenagers who think their job is to empty my cupboards as fast as possible.

Positives:

• I have a slow cooker and an instant pot and am not afraid to use them
• Both girls are fairly competent in the kitchen (when they aren't a training/work/social stuff), so will be able to help with prep.
• other than the specific issues the girls have, the 4 of us are fairly adventurous food-wise
• I'm a pretty decent cook. I've just totally blanked on what to do here.

TLDR: please can people suggest some easy to prepare meals for a crowd, that aren't hugely expensive, and that I won't be embarrassed to present to guests, to save my lovely MIL and BIL from being fed bolognese every night because I can't think of anything else. (Added bonus if there are lunch ideas other than "have last night's leftovers or a cheese sandwich" which is pretty much the standard instruction in my house) I have 3 weeks to practice...