I worked on the fragment engine (and the envelopes and their editors) so that there can be parameters which can leverage multiple envelopes. (Namely the most suitable parameters are/would be Source position, Transposition centre, Fragment length, Panning centre and Fragment volume.) The fragments cycle between the “sub envelopes” in a round-robin fashion by default but custom play sequences can also be set up.
So what is this useful for? It allows for creating at least an illusion of multiple texture streams going on at the same time until a more complete system for that is implemented. (Which would probably be something like a timeline of multiple lanes/tracks of fragment textures, but that’s a pretty involved thing to implement and will probably happen around the 2.x versions time frame. Or could be a thing for a whole new application…)
The feature required an unfortunate amount of changes in the code, so I am not sure if this will appear in the next public builds, but it will definitely be incorporated at some point.