How can my child make their wishes known in a custody hearing without the other parent knowing that they expressed a preference?

You can ask for a private conference with the judge. How old is the child?

It would be impossible to do. All information is shared with both parties at some point when the decision is made. The best and about the only way to have a child express a prefference is to go through a parental evaluation. That way a third party can check the entire situation. Then make recomendations to the judge. Most children can be easily swayed when it comes to divorcing parents.

The judge, can talk to the child, alone, without either parent there. But what is said, will become part of court records.

Also something very important... is how old is the child. (Just noticed ScottGem asked that) because below a certain age...the childs wishes mean little as the court decides what is in the best interest of the child.