Wow, quandrea....
I am PROUD of you!!!!!
You really have come such a long way in understanding this whole thing, and trying to deal with it.
Things that I learned over many years/decades of dealing with this, and research, etc... And I had the luxury that it wasn't MY parents/family. Which is always much much more difficult, when the waters are so much more murky, emotionally entangled, and one cant see the forest for the trees.
I will just say that I am noticing a few little comments, starting with the very beginning of your thread here. Comments like, you want to to speak to your sister about things like your children's birthdays, you 'asked' a sister not to say things regarding family news (negative towards you...), etc. etc.
I think that this situation here might be the next step for you ...
You have not truly disengaged.
You still want to try to discuss with these family members and hope for a better outcome.
Now that you reach this point that you have, you might want to consider that you need a slightly different angle.
Because any 'discussion' or 'asking' is not going to get you the results you hope for.
If there is one thing that can be said about a Narcissist, it is this.
Never 'question' a Narcissist...
And Never 'ASK' a Narcissist for anything...
Ohhhhh, and another huge one, a narcissist can never be 'blamed' for anything, any of their actions.
Like, for example, the topic on this thread is how to 'get out of Christmas'.
And, the simple answer is - you just DO.
Perhaps, your real question here is 'How do I get my dysfunctional/toxic family members to let-me-out-of-Christmas'.
And, given the info that you have put forward here.... You do not..... They will react how they want.
You have to just recognize that, and let that be what it is.
Remember the age old adage: You can not control or take responsibility for other peoples actions and feelings, but you must and should take responsibility for your own.
You also mentioned a sister who has her position based on the fact that she just wants to be non-confrontational.
She does not want to be assertive.
The basic and true and given fact of the matter is that this inability to be assertive (forget confrontation, totally confrontation is NEVER a good idea) but the lack of being able to be assertive about one's own life and personal boundaries is the EXACT factor that a Narcissist will zero in on when identifying and choosing victims... It is kind of like what I call being a 'WILLING victim'.
A willing victim is still very much a victim.
By definition, a person who is able to think, "HEY, screw this... I don't need or deserve this." and simply walk away....
By definition, this is not a victim.
This is not a person that a controlling abusive narcissist will be able victimize. (they very well know this.)