To answer your question, yes, I have seen one. However, that was at a gunshow a few years ago. I would try looking at marstar and some of the stateside online gun parts warehouses.
The real question is what variant of the Star model B does your son-in-law have? There were two main types, one in 9mm largo and one in 9mm luger. From what I've read, there's no easy way to convert one to the other.
Check out the forum at 9mmlargo.com.
Good luck!
-John