I'll start by saying 99.9% of new aquarists don't know why a balloon is shaped as it is. The fish has a serious spinal deformity, cultivated by fish farms because it sells well. So she is squaring off, as breeders say - it's a shape seen not long before she drops her fry. With her severe scoliosis, the shape is kind of wonky.
Personally, and this is just a stranger on the internet talking, I wouldn't raise the fry as they will have the same genetic disease. A lot of female balloon mollies die giving birth, or soon after. I hope she's one of the lucky ones.