How do you meal plan for household with teens/YAs?

[Argharghargharghargh]

How do you meal plan for variable numbers of people/times/preferences?

Things will change again when they go back to college and school in September, but right now I am baffled as how to organise meals and food shopping this summer with both kids at home after exams, but also with their busy social/work lives and randomn plans.

I can't work out how much to cook or even what to cook and how to shop for this atm. Some nights all four of us are in, sometimes three, sometimes 2, sometimes just me. Sometimes they are back later, sometimes rushing out and need to eat early. I am finding it really hard to meal plan. If I cook from frozen, I can't reheat. If I make too much some goes to waste. We end up with random left overs that no one wants, or not enough for everyone. Also sometimes they bring friends back and we need food for 5 or 6. 16 year old still needs to be reminded to eat properly and regularly and doesn't really cook for themselves. 20 year old is self-sufficient, but it feels wasteful (and expensive) to be cooking two or more different meals in the same kitchen. Asking them to say what their weekly plans look like is pointless as it changes on the hour! DH will cook for everyone as usual and then hoover up what's left, but that isn't great for his health!

We have just about nailed lunch now, as everyone pretty much does their own thing, but I can't quite cope with that for dinner time. I don't know why I am so confused, but routine has entirely fallen apart this summer, and I am not quite at the point of everyone just doing what suits them when it suits them. I would like to say dinner is at 7, if you are here you are welcome and there will be enough food (do I cook for four every time?), but if not - then what? 16 yr old already spends far too much on takeaway and crap food if out.

Maybe it's glaringly obvious to everyone else? Also we don't have a microwave - I suspect this may be the real problem, but I really don't want one. I am sure people will say the 16 year needs to learn to cook and I agree, but knowing how and actually doing it are different things and a third round of ingredients, washing up and shopping doesn't seem sensible

Flexible meal suggestions most welcome, but any insight on how you manage this would be really helpful. This is making my brain hurt and the eternal conversation about who is in and who is out is driving me mad. I used to be good at this stuff!

when do you do all your batch cooking and prep?

I didn't 'set aside a time to batch cook' when mine were all at home but working shifts, I just cooked a normal size family meal - as per the previous 15 years or so - and, if they didn't eat it that day, hen they had it to take into work with them the next day, or eat when they got in, or whenever they were hungry.

Not sure how you would do this without a microwave though.
We use the slow cooker quite a lot in Winter, but that only really works for keeping warm for an hour or so after you've eaten. When mine were that age, they might eat 6 or 7 hours later, or, sometimes the next day.

Also, all of mine had to take a turn in cooking from when they were at secondary school, so they "got" the concept of wanting to know who was in for which meals etc, and how annoying it was to cook something nice that no-one then turned up for, or the idea of the fact that when people were going out quite early, the meal had to be on the table early so that affected what you choose to cook, etc etc. Also, of course meant they were perfectly capable of making themselves something if not eating with us.

An easy way to batch cook(once you get int he routine is to nake double so-if you do a spag bol just cook double and freeze. Then tou end up only cooking half the time and using freezer supplies the other half.