Go for it if you want, but personally I wouldn't join. Just doesn't seem quite right somehow. Closest comparison I can think of is turning up to a party in a snazzy dress, to see someone else wearing one just like it. Except you knew they were wearing it, and chose it anyway. It'd be weird.
what about make sequel to a cap in haven not made by you
I'm never comfortable taking over someone else's work- A, it srikes me as unimaginative, B, you're limited to their rules. Plus, I'd worry so much about not messing up pre-established rules and continuity that anything I did write would be crap. Hell, I rarely even use well-established 'classic' captionverses like the Great Shift or Medallion of Zulo because of it.