Kids make the wishes.
Grown-ups make them happen.
Make a family page, let the kids add what they want from Amazon, and share the link. Relatives claim a gift and buy it, so nobody doubles up.
Kids add wishes
Paste Amazon links or a whole Amazon wishlist for each kid.
Share one link
Send it to grandparents, aunts, uncles. No accounts needed.
Claim & buy
Adults claim a gift, then buy it on Amazon and ship it to you.