So do I hand over details of my coins to my brothers for now, and if I eventually make it to have kids, how do i then retrieve such Information and make sure it is solely with just my kids?
That part is actually pretty trivial. If you hand over your seed or private key(s) (encrypted or plaintext) to your brothers right now, nothing is stopping you from creating a brand new wallet with a new seed and swipe your old wallet to your new wallet once you have kids. The proceed to give the new key(s) or seed(s) only to your children.
That way your brothers could spend your funds if something happened to you right now, and later on (when you have kids) you can rest assured they're not going to be able to steal your children's inheritance once you pass away.