If most adults coming normally bring a bottle of wine, could you ask them to bring something specific instead?
So say you did a couple of big trays of lasagna for the "Aunts and Uncles meeting DC" event - ask the visitors to bring
Couple 1 - a big bowl of salad
Couple 2 - a bowl of coleslaw or potato salad
Couple 3 - a bowl of fruit salad or something for desert
And you throw a few garlic breads or part baked baguettes in the oven with lasagna, and add a bowl of cherry tomatoes and some salad dressings. And lasagna can be bought, or made ahead of time (and frozen ahead too if you have space).
Christmas Day: Things to ask for could include
A starter - smoked salmon and a loaf of soda bread, couple of lemons to garnish; prawn cocktail ready to just serve out; LARGE pot of soup; or a few trays of nibbles to eat while final preparations are made and people are chatting and mingling (no "starter" at the table? Or as well as a starter?)
Side dish of veg 1 - say carrots
Side dish of veg 2 - say Brussels sprouts
Side dish of veg 3 - say French beans
Side dish of veg 4 - say red cabbage
Large bowl of mash
Stuffing? (Or do you like to stuff the bird yourself?)
Ham, cooked and sliced already - which can be eaten cold or heated through in oven while turkey rests
Is anyone FAB at gravy or bread sauce or something special?
Pudding and/or desert
Cheese and crackers?
You do turkey, 1 roast potato each (a few spares but expect people to load up on mash), have a bag of frozen peas in the freezer in case you need more veg, possibly stuffing, possibly gravy, and have ice cream and jelly for desert (jelly for kids, but lots of adults like it too I find!), possibly a bowl of whipped cream or some brandy butter etc might be needed too, and having tea/coffee, and choccies or biscuits for later as well.
Boxing Day:
People can bring things like sausage rolls, pork pies, "Auntie Maeve's turkey curry" or whatever.
You could do leftovers in sandwiches (we traditionally have ham sandwiches, turkey sandwiches, Christmas cake, mince pies and Guinness on Boxing Day). Use leftover veggies from Christmas Day to make soup.
New Year - do something simple that needs long slow cooking in the oven. A slow roast, or hearty stew type meal. Lots of those use cheaper cuts but taste divine having cooked slowly! Here, I'd ask for starters, cheese and desert to be brought, maybe a side dish of veg or mash.
Plan ahead now on all meals.
Write down your lists and start to gather ingredients as there are special deals on (BOGOFs, lots of threshold spend vouchers in supermarkets at present, etc).
Include things like plenty of bin liners, kitchen towels, loo roll, tissues, and some extra cleaning products. (Eg. keep a spare bathroom cleaner spray and bleach upstairs out of sight, to be able to do the bathroom in 5 minutes quickly, and adopt cleaning wipes for the duration for quick tidy ups). It's not that you will only "swish and swipe", but do a decent clean ahead of time and all you need do over Christmas week is a quick swish to make it all sparkle!.
If you have any freezer space, get ahead with things now. So things for meals in between times for your small family to cook and eat quickly with little fuss - pasta sauces, curries, chilli con carne etc. Side dishes for big meals, or things like sausage rolls/mince pies for passing around in large, "not really meal" gatherings.
Or whole dishes - so say you make a family sized lasagna this week for dinner but make 2 and freeze the 2nd for family meals over Christmas or the "meet the baby" event. Once frozen, pop it out of the dish, wrap in a couple of layers of tinfoil, LABEL, and pop back into freezer. When you want to defrost it, unwrap from tinfoil, put back into original oven tray and let it defrost there to cook when you want it. As long as you use different containers (or have more than 1 the exact same to use for larger events), you could do this a couple of times and have enough made for a bigger event to just cook on the day, no other work needed.
Also, once you have your menus done - DELEGATE.
Ask everyone who is coming to make something for it, and be specific if you can. "Could you please bring a bowl of salad leaves to serve 16 of us?", "You make such wonderful coleslaw, could you bring a bowl for the 16 of us please?", etc. Or ask them to be responsible for a course - "I can sort the turkey and Jane is bringing vegetables, but could you please organize the starters - I don't mind what it is as long as it doesn't need to cook in the oven", "You always have such a lovely mix of cheeses after dinner in your house, could you bring the cheeseboard and crackers?"
Prep ahead of time.
Peel veggies and potatoes, make stuffing etc, on Christmas Eve.
Give out jobs when people arrive - minding children, serving drinks, setting the table, gathering everyone's coats.
Although the more I think about it, THAT many events, in so few days, with a 22 week old and just turned 2 year old, sounds fairly full on. So if you cannot dampen down expectations (fewer events and low key ones), DEFINITELY build in time that is just for you 4 as a core family - to sleep and rest and enjoy together, and to catch up in the house.
DH needs to be on board and do lots. And I would be half inclined to have a cleaner come in the week before Christmas to blitz the house and make up any beds needed. And to buy in a lot of pre-prepared food.
And I m right back at the start then about high cost without having answered the original question. Sorry about that 