No, really...this IS for a friend!

I've got a friend who breeds Shih-Tzus and is concerned because her two females aren't coming into heat.
This is what she told me, so hope I'm getting it right...
About six months ago, the stud dog that she had, whom the females liked and were used to developed three suspicious bald patches. The location of the patches could indicate either hypergrooming or Cushing's Disease.
She retired the dog to a home with kids where he's being spoiled rotten (I mean this in the nicest way).
She then got this new male...said the females were in heat, but they wanted nothing to do with him.
Fast forward six months to NOW...

Females don't seem to be coming into estrus, and they're not all that impressed with Mr. Stud.
I don't know the dogs, have never seen them interact with each other.
Is there anything she can do to...well...sort of help things along?

I was thinking maybe oxytocin...you know, the bonding chemical your brain makes when you fall in love or you're nursing?...but I'm not a vet and this is probably a case of a little learning is a dangerous thing.

The fact that they haven't come into heat most likely has nothing to do with the male, when a female is ready she will come into heat. She can talk to her vet, but most likely she just needs to wait it out.