QB, you really are better off using a made-up name for the seminary, especially if your character goes there and anything important to the plot of your novel will happen there.
If you want her to apply to a few sems and then have her go to your fake, you can do that – use a handful of real names from the ones people suggest above and list your made-up name among them.
For made up names, you can either use something like Bnos Sara (which is good b/c it looks like the reference is to Sara Schenirer AH) or Bnos Torah, or Ateres Bas Torah etc. Just do NOT steal any names of Creedmoor sems, like Bnos Burqa, or my trademarked “120-denier seminary” line!
-Hatzlocho