Well I cannot comment on the difference of preferences for what type of Poly that you and your husband have, other than to say that's an issue you two really
need to find some common ground on. And soon.
As for holidays and secondary partners and their expections.....That I can give you an opinion on:
For about three months currently, I have started dating a married guy with kids. And I am on very friendly terms with his wife.
I did NOT spend Thanksgiving with him/them, and...I do NOT expect to spend Christmas day with them either.
A nice holiday date with him about a few days before Christmas, where I can spend a little time with him, exchange a gift, have some good holiday food, whatever----yeah, That is a VERY reasonable expectation.
To spend actual Christmas day with him, his wife and kids? I would never ask that!
(And this early in dating, I'd probably even turn it down if invited. Too soon---maybe next year.)
In the meantime I just wanna put some effort on trying to find my own primary partner for this and future holidays.
So that's my two cents.