Um, a little bit of history may be relevant here.
Many many moons ago, when Jupiter was aligned to Mars, on the far distant planet ZPrX the idea of "transforms" was born. In those heady days, when small furry beings from Alpha Centurae were real small furry beings etc etc etc (apologies to all concerned) ....
Anyway, when the first transform thingo evolved, one of the Sparxians provided, at my request, a transform that would take a (very simple) sequence diagram and transform it into what was known then as a "Collaboration" diagram. I never realized that it ever got released into the wild.

In those days, collaborations seemed to have real future and were pretty good value. Alas, the fortunes of humankind seemed to have moved on.
(Its nice to see, though, that at least Fabrico seems to value them still!)
Nevertheless, it was (cough) pretty much of a hack, even back then. It was, AFAIK, never meant to be a core EA tool or even a peripheral EA tool. However, if you guys want it, I can't see any reason not to raise it as a feature request, but I would hesitate in casting either ancient Greek or floral aspertions. 8-)
cheers
bruce
p.s. The entire above was written by my father and I accept no responsibility for anything relating to his memory or lack thereof. S-O-S