My understanding is if it's sterile it will not produce viable seed no matter how many crosses you make. It's a mule and will not reproduce.
If you wanting to grow plants from seed you best bet is to let the bees work and harvest any seed you get. Not all the hybrids are sterile.
I grew heuchera from harvested seed from my plants and saw some interesting results. There is a thread on his forum. I'll see if I can find it.
