You need to set some boundaries. This will be easier as you have time to send an email in advance making things clear.
All meals are not provided by you and DH. If they are guests they should be bringing food special treats drink, etc for the celebration with them. You state you will cook Christmas Day, cold buffet or left overs Boxing Day. Other days it’s initially what’s in the fridge or what they’ve brought and take it in turns to cook. Then when it runs out (don’t get too much in) whoever’s turn it is has to go to the shops, buy ingredients and cook. Will also mean daughter and partner have to go out and give you some peace every other day and your day you get to go out and buy ingredients. If they don’t want to cook on their day they have to plan and PAY for a takeaway, pub lunch etc. That’s their day to pay for not yours.
oh and breakfasts and lunches everyone helps themself too and replaces what they eat or drink.
Some days are downtime, personally I’d make it every other day. So those days it’s a lay in, quiet day at home doing separate hobbies maybe just plan to have a hot choc and a mince pie all together mid afternoon or something. So they are free to do what they want and then a bit of time with you two. The way I’d personally do it is set up an activity jar in advance with activities written on paper inside. Each time your daughter ‘has’ to do an activity one gets picked out. But put ones in there that are quiet and relaxing activities like a walk, watching a film together, a board game or cards, a pamper evening that sort of thing. And it’s only one activity per day.
Plus also set things up so if she’s bored and it’s a small house there are things to do together or separately. So Christmas jigsaws, start one before arrival so that’s something all doing together but also separately. Have a pile of Christmas books and magazines out to read on the side or reference/hobby style books (secondhand from the charity shops and a massive pile of library books so no cost), set up the radio somewhere quieter away from the tv and mark in the radio times or tv magazine the things you or husband are planning on listening or watching, they can do the same so then it’s known in advance you are doing that alone at that time, put some puzzle crossword books, pens, cards and games somewhere else on the side. All these sorts of things.
Also if you and your husband have hobbies mark them on the calendar that you are doing that at that time away from the house, or in the garden.
If it really gets too much say you are going for a walk or drive alone or go and run a bath or have a nap.
Hope all of that helps….also say in advance in email the dates you can do so say arrive Christmas Eve can stay 7 days, that sort of thing.