Of course I know that a flow isn’t a piece or movement etc. and it can be used for sereral other things. I just assumed that, for a “simple” piece like a Waltz & Trio, there’s no need to split the music, except you have some specific layout wishes in your head.
Here’s one of the threads, where this topic was discussed. Included are some workarounds. Most workarounds will kill a proper playback. So if you need a layout with a coda or an additional flow, you need dedicated solution (probably flow) for the playback.