I searched but couldn’t seem to find this request (though there are many topics about how to combine systems into frames).
I’ve just started using the key commands for Move Bars to Previous/Next System - I’m not sure why it took so long but I’m now at the party!
It’s now a little annoying having to manually select two items in different frames in order to use the Make Into Frame function. I’d love a function to be able to squeeze systems into frames i.e. with one keystroke.