I think I would move the plans around a little bit. Apply for permission for her to marry while still on the WP. If she obtains that, then marrying her is not a problem and you can then hire her on an S pass. Won't be any issues that way. Is she currently working for you or someone else? If she is working for you, more's the reason to do it now before you get her an S pass. That will alleviate some, if not all of the suspicion re S pass/kickbacks.
Additionally, which I failed to mention in my first response, it makes no difference if she is on an S pass as you will have to apply for permission in any case, even if she is on an "EP". The rules actually state that permission is required from MOM if the potential spouse "has EVER worked on a WP" not just currently. So you still have to apply for permission to marry and it makes it even more necessary to apply now while she is still working on a WP to eliminate any of the concerns mentioned.
For the rest of our regulars (no need to continue) who know the issue with my nephew's daughter who I've been taking care for the past 12 years, his wife, from the 'peens was actually a degreed English teacher in the 'peens but took up a WP job here many years ago. Went back to the 'peens for a couple of years and my nephew actually flew to the 'peens, they got married and she got pregnant and they came back to SG where they gave her an LTVP so she could have the baby here, but after that they would not renew (but the baby has SGC as the father is an SGC), she was banished back to the 'peens because they never got permission from the MOM even though she'd been back in her country for 2 or 3 years.
SOME PEOPLE TRY TO TURN BACK THEIR ODOMETERS. NOT ME. I WANT PEOPLE TO KNOW WHY I LOOK THIS WAY. I'VE TRAVELED A LONG WAY, AND SOME OF THE ROADS WEREN'T PAVED. ~ Will Rogers