You help your kids give her gifts. You do this every year.
Since your kids are young, I would do something like a hand print gift. I had a DIY pottery place that I took my kids to. We made a serving platter with our hand prints. In your case, just have D4 hand prints and son1 foot print.
The point is have it personal from the kids, not you. Always be a great dad.
"What is best for my kids is best for me" Amor Fati Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712