This wasn't a poly thing-but when we had a "his, mine and ours" kid situation, we commonly rescheduled holidays or duplicated them.
We did Christmas on New Years for YEARS. (great for getting after Christmas specials.
This year we're doing Thanksgiving a week early.
As a child-my parents both worked in the medical fields-so we did holidays on alternate days as well.
"Love As Thou Wilt"