I dont see any harm in feeding her the WM formula.
It's the quantity (amt you feed) that will determine if it's WM or regular food source.

When Skinny had all his coccidea problems and after 3 different antibotic attempts plus other stuff, it was the Nutro Weight Management that cleared his potty to regular toostie rolls.

My experience and research (which has been quite extensive) is corn and all it's byproducts causes runny poop not fat content percentages. Better the food the firmer the potty

Our new vet didnt even consider more antibotics. After 3 attempts they arent going to work. You then have look for a food source problem. We did and it cleared up.

It's not going to happen over night but within a week or so eating good stuff you should see a big difference in the poop content.