Childrens activity pack

If it's not too expensive you could have little stockings instead od bags to put their stuff in?
Of not then you could put in drawing book, colouring pens/crayons..maybe a xmas book? A little Christmas personalised bauble or tree decoration? Christmas cookies or gingerbread santa man, the little Christmas chocolates you get? And a little toy to suit their age? xx

Or instead of a toy a little reindeer / santa toy/teddy?

Wind up Christmas toys and let them race

Instead of the usual wedding activity pack, how about a christmas and wedding themed one? You can create these in MS Publisher - have them decorate xmas trees, reindeer, santa with stickers etc or have them make xmas decorations to be given to the bride & groom after? for the smaller kids, just give them mini stocking with small toys wrapped up & they'll spend ages unwrapping them!

I have made up some activity bags for the children attending my wedding, I have included sticker books, colouring books, puzzles, finger puppets and little novelty items. Got a lot from this website, cheap and cheerful! https://www.allaboutpartybags.co.uk/