Hi John, great to meet another Patent Etui owner Probably the most under-rated small pocket-able yet practical camera made. I have 2 9x12's and a load of 6.5x9 plate holders to sell The 9x12 Patent Etui's are essentially LF cameras that fit in a pocket.

I've quite a few 6x9 Roll film backs Rada and Rollex (for various cameras) and they all match the register of plate/film holders, film packs etc, so yes you can focus on the GG and then swap to the Rollex.