There is no such motion required, or normally required. Upon the filing for custody (initial or modification), the Court can confer with the child in chambers (in the Judge's office) sua sponte (at the court's own motion), meaning the Judge will say "Does the child have a preference, how old are they, okay let me speak with them."
OR, either party can file a motion to have the Judge confer with the child, but often, this is done (as above) anyhow.
The Judge will confer with the child, because this is the only way that they can get the child's preference. I have never seen a Judge DENY conferring the child's preference. So while some argument can be made up why they do not have to, I doubt that the Judge will not.
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