I think it’s great that you’re encouraging your kids to search. That’s not an easy thing to do and I hope that some day the birth mother you found will be open to a relationship some day. As for the other child, I wouldn’t push. If your close relationship continues into adulthood then he / she will know that you are supportive of whatever they choose. Finding birth parents is good for some kids but maybe not for others and it all happens at different times in our lives because we’re all unique. Nobody likes to be pushed or feel pressured into something even if it is for positive reasons. You can tell them that you will support their decisions now and in the future, no matter what, and that will be remembered, I’m sure.