All children should be removed from whatever adult they are with until it can be proven that they are related at the very least.
Wouldn't it make more sense to keep the parents with their children, but coordinate with the Mexican government to vet the immigrants by matching them to their known identities, and whether or not they actually have a child? Interview the children. In extreme cases, but I don't particular care to assume this cost, we could analyze blood samples.
Frankly, I think we need to begin fining the Mexican government in some fashion. They'll start caring about this problem once it hits them in the pocketbook. We give them $320m in aid a year only to have posters like
@Rod1 come and spit in our 'stupid' American faces over and over. There's plenty of leverage, there, without even dipping into tariffs which takes the fight to a place it doesn't really belong.
After all, most sexual abuse of children is perpetrated by men
within their families. You're going to separate the children from their custodial predators only to put them back together once you confirm their genetic relationship. You're reacting hysterically by forgetting the shape this beast takes, or perhaps you are simply ignorant to this shape altogether.