Praying for the family. With death in our family, it felt good for the kids to do things: flowers to grave, or church, or sent to some other older person still living (done in honor of the deceased grandparent), gestures and helping others, sorting photos, making cheap copies and creating albums, collages, bookcovers, t-shirts, etc. Doing something that the deceased used to do: go to beach, attend their garden club or even poker night with their old friends (call the friends/club in advance), throw a oarty for those who loved the deceased, or took care of the deceased (if they were in a nursing facility-ask if you could throw a little party for staff and patients.)
With the dog loss, my sister does this with her students: she has them write “20 things we loved about Fido” and then she posts it on the wall with photos.
Kids love to give things meaning.
Also, when my folks died, my brother started new traditions for every year: The circus, the snow, a restaurant, a picnic, a hike, AND he followed through with it every year until they grew up and got busy.