Well, we can start with posting "Dog Hill" by Boo Zoo. It is being played on a B flat accordion, but it is being played in the key of "F" (aka on the pull) (aka in the fifth b,c,d,e,"F",g,a,). I don't play a B flat accordion though. But I can play along with this song in the key of "F" on my "C" accordion. If I can do that, you should be able to follow easy on your B flat. Zydeco uses buttons 3 and 7 together on the pull to intro many songs. Pre-seaded by a short press on button 6 on the pull of course.
I don’t think boozoo really knew exactly what he was doing either lol. Not in a bad way of course. Sometimes you just roll with it baby. I remember him saying to the band in one those live recordings follow me.