choose a proper gifts to the kids is a huge project, especially for the parents.
So what is the best thing you send to the kids?
What do you mean by 'send' to the kids? Are you not with them? I'm not asking 'why', I'm simply asking if you're not with them.
If that is the case, I think that 'time' is and always will be the best gift. They might not think it or indeed say it or thank you for it at this point in their lives, but later on they'll look back and remember those times. We all remember toys, gifts we received as children but we remember the good times we had more than that. Take them out, make a fuss of them. It doesn't have to cost much money. The local park, beach, field etc.