I've seen several threads relating to retrieving a firearm from parents while in a different state and understand the problems involved, but have this question:

If the non-NFA firearm is owned by a Trust and the Trust has the parents and the adult son as co-trustees, and the firearm is legal to possess in the new state;  can the parents transport and deliver the firearm to the son in a different state?

Am I correct in assuming that no "transfer" in the meaning of the GCA has taken place since all involved parties are part of the trust?

A trust is not recognized as a "person" in the GCA, so you would still have to do the FFL transfer route.