H and I both do not share birthdays or Xmas with our exes. Both exes get Xmas Eve or in my case my ex in-laws. We get the girls Xmas Day. Honestly my ex in-laws are far more likely to be with us for D17's birthday than they are with my exH. My exH on more than one occasion has completely forgotten her birthday or never got her anything or both. For D16 it's a weekend prior and weekend after and who ever's weekend it is that's their birthday weekend. Their 50/50 switch off historically was Saturdays so it just always kind of worked out even if her Bday fell on a weekend. Kids especially young ones are easily won over by the concept of a long and stretched out birthday with multiple celebrations. Same with Christmas. They adapt. It's really more us that have to reset our brains that things have changed. We have to let go of those expectations we had about all those future milestones and hoildays. And in those early years being alone is hard, but it's best to make plans and keep busy. But for most of us we meet someone new, we develop a new routine and new traditions, and it all just kind of becomes your new normal before you know it.