I believe that you can bring the firearms over the border to an FFL in MO and let them complete the transfer.
It would be a nice present to say "Let's go looking" and stop in at the FFL with your Dad and brother.
I would set up with the FFL first.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
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Life Member NAHC