It was the policy before Trump came in of the 9th circuit courts that ruled it in-humane to keep kids and parents in jail holding cells in the Reno V. Flores case 1993.It was not the policy of the Obama administration to separate children from parents at the border. There are times it still happened, usually because the child was suspected to be in danger, but it wasn't the policy across the board as it has been under Trump. Now CBP and ICE are the danger to these children because they either lose track of the parents, sexually assault these children in custody, or in several cases, let them die in custody.
And they can’t be released to anyone other then a parent or guardian. So if the maybe parents is in jail for illegally coming in the country then the children are placed in a children’s detention center until the parents hearing. To verify that the kids aren’t victims of child trafficking and to verify they are actually the real parents.