You only need a signature* to buy NFA items, so since you're specifically asking about stuff you already own, there's no need for anyone's signature (a reason the whole signature thing is incredibly stupid).

When you move, send in a 5320-20 (up to 3 NFA items per form), mark "No" to question 2 and you're done.

Yhea I know it says "Transport Interstate" but if you move, they like to know

O2

*If you're doing a individual transfer. Trusts, etc. require no signature (another reason the whole signature thing is incredibly stupid).