That seems odd , I just assumed that the hybrids were wild caught and man made breeding situations. I would guess that if rtcs and tsn have been breed in captivity it was done in asia somewhere.
Yep ^^ In theory though in test tube situations similar to tsnxrtc, and tsnxp. niger it should work though unless something in the hybridization makes them infertile.
But yeah not something you can do on your own I don't think.