Which Byzantine imperial dynasty, incidentally ? There was quite a few of them over the centuries...

There was also that one Danish king at some point of the 19th century, I think, who had a whole slew of daughters he managed to marry off to other royal houses. He's apparently sometimes known as "the father-in-law of Europe" for that. Mind you, I've also read that annoying little hemophilia came to the Russian imperial family that way...