DH and I live away from our families, although not abroad. Until recently, it was only my job that insisted on an appearance on Christmas Eve (well, turn up for an hour or so on 24th in the morning, or take the full day off as leave - building closes by about 12.30pm in city centre) - but DCs are welcome to come in and we tended to join DH after he'd had a coffee and wander locally for lunch, last minute shopping and travel home together again. In 2019, his company changed their normal and also opened on 24th, UK HQ were demanding full working day until 5pm but DH (as the most senior) took an executive decision on his office (geographically same time zone but not in UK) that it was only until lunch.
But when I went into work, DD enjoyed coming to see my colleagues (and getting to raid biscuit tins and chocolates boxes all over the building!). We had a nice lunch in town with DH, and made a last visit of the season to the Live Crib outside the Lord Mayor's House, got a few bits and pieces shopping (including DD picking her birthday cake in M&S for 26th).
We try to get a walk in if the weather is ok - often the woods near home. Some years if we have not been at work (taken leave or weekend days), we have done the Christmas Eve swim for a homeless charity in the local sailing club and enjoyed meeting friends there (for the swim, and a warming drink afterwards) before it closed for a few days.
Our afternoon has always been working together in the kitchen with the radio going for festive cheer - DH, DD and I - to prepare for turkey dinner. Peeling and chopping veg, making stuffing, playing tetris with the fridge to make everything fit etc. DD has always baked cookies to leave out for Santa as part of that - some years from scratch, but there is always a half a batch of dough in the freezer from an earlier baking in Nov/Dec that we can slice and bake if proper baking is too much for us that day.
Our dinner is a selection of lovely things laid out on the table for everyone to help themselves. Mostly cold, although there might be some hot sausage rolls or 1 other hot thing some years.
After dinner, DD lights the Christmas Candle - an Irish tradition that shows that there is room in our "Inn" for any weary travellers needing shelter. In our case, we take the time to reflect on the good and bad of the year that is finishing, and remember those no longer with us, and say a family prayer.
Then the Christmas Eve hamper comes out - with DD's plastic plate and glass with Santa on (from being a toddler), her stocking, her snowman covered hot water bottle (that's in use all winter), the family edition of "Twas the Night before Christmas", new PJs for everyone for winter, hot choc for all and a christmas craft beer for DH, and lush festive bath bombs for DD and I.
It's the signal to her to lay out the milk and cookies along with the stocking, before going up for a relaxing bath. Into new pjs, comes back down for hot choc and a cookie, before we read her the book as a bedtime story all snuggled up.
Of course, if we are having a travelling year, we are either doing a lot of driving to get home and visiting both houses before bedtime, or doing things with various family members all day and making sure to visit both houses before hopefully getting to where we're staying at a reasonable hour.
Both of our work gatherings are before 24th. It's varied over the years between a lunch and a dinner, and what date it might happen, but I think the 22nd was the latest ever. 24th is a day when everyone wants to do family things or travel.
But if you know that it's likely to happen again, plan on what you want to happen with DD generally as solo activities and keep something special to do with DP in the evening but assume he won't be around until then. THere are lots of crafts or baking or festive walks or wrapping special presents that you could do together, listen to Santa's phone-in on the radio in the afternoon, look at the Santa trackers (Norad, Santa Update etc), make a paper chain to decorate her room, get her to help clean up as an especially "Good list" thing, dance around to Christmas songs, watch a Christmas movie and have a carpet picnic instead of lunch/dinner.....
If DP will have a large meal with work, maybe get something that DD and you would really love and is easy, and have some snacks or party food bits to have later with DP in case he is peckish. Or have your large meal during the day also, and have your family meal being smaller and under less pressure of time - especially if it's more snacky bits if DP gets delayed that DD can have some carrot sticks and cheese and ham, but might still have some more when he gets home. Rather than trying to rush a proper dinner together.
What I love about 24th is that it is a day where we start to slow down (as we race around far too much in our house always), we wander in town as we generally have everything except DD's cake bought by then so it's bonus things but we don't need to do lots of queuing (and M&S queues generally disappear very early in the city centre once the pre-orders are collected). We like to get some fresh air either with a walk or swim, but by early afternoon at the latest. We don't have that much to do in the kitchen but we are doing it together and chatting and spending time hanging out together. Dinner is open things and put them on the table, no rushing to cook complicated dishes, and we enjoy sitting over a long relaxed meal. And we keep slowing it down afterwards with the candle and fun but gentle times towards bedtime.
If DP's job has a certain way of doing it, then you probably have to adapt to that. But there are lots of ways you can adapt, still have fun with DD and later DP. And also, while you might not get to do some pre-Christmas fun stuff with him on 24th, if he has the following 2 weeks off, there can be lots and lots of family fun in that time!!