As a step parent. I came into my DH life knowing that his son and X would always be a part of his life and they would always be a family though not together any longer. I have always treated it, for SS because he is a child and didn’t choose this situation for himself, like we are one extended family as much as I possibly can regardless of the ups and downs of working the emotions in the situation between his mum and dad at times.
DH and I don’t have children together, but his mum and stepdad have 2 further children. As heartbreaking as it is for my DH Christmas Day for us is a very quiet day with just my mum and grandad having spent Xmas Eve with his mum and dad. So SS has Xmas Eve and Xmas Day with his mum and family as there are other siblings he wants to be with and play with.
We pick him up Boxing Day (he lives 30 mins away) at 9.00am, go to my DH parents for the morning to do gifts and have some fun (DH is an only child and his mums not big on Xmas as it’s been traumatic for her in the past), then head to ours briefly to see what gifts Santa left at our house and then head on to my mums where my brothers and their children all come and have the best time! So Boxing Day is more like our Christmas! Then we have his for a couple of days and drop him back thereafter until our rotation comes round again.
You have children in your home too that your SC are going to want to see as they are their half siblings too. I don’t think alternating Xmas Eve/Xmas Day hurts so long as the children are happy with this. It allows everyone a far more relaxed and less stressful day to enjoy TBH, so I understand your point.
But, what I will say is this isn’t your decision, they were here before you and you need to accept and respect that and, whilst you can have a quiet chat with your DH about what you think, none of it is your decision I am afraid IMHO that is then up to him if he’s happy to work that out with consideration of the fact that it might even work better for his children in discussions with their mother.
we also do all pick ups and drop offs, but we don’t care, if that’s what we need to do to see SS that’s what we do, simple as that.