This is normal. It is developmental based... thus, you can't "make" the baby stay on their back or in the same position.
At a certain age(s)... a baby naturally will begin to have new "skills" and motor skills... ie: rolling over, sitting-up, pulling up and standing etc.
A baby will do this even when supposed to be sleeping... it is instinctual. This is how they "practice" their new skills.
At each age-juncture and whenever their new motor-skills emerge... it WILL tweak their sleep.
It is "good" that your baby is now rolling over.... she is developing normally. But yes, it will wake them, because at this stage and age, they do NOT "know how" to make themselves go back into a proper sleep position by themselves nor to adjust themselves at-will... yet. So yes, you will need to help her... or, you let her just be on her stomach. And yes, it can be repetitious and wake them.
But, I would not yet, put a blanket in the crib with her... she can get tangled in it etc. Not safe. A baby this age does NOT have the skills nor ability to at-will pull the blanket off, IF it should get across her face or tangled up in it.
This is all part of growing-pains, for the parent. As the baby is changing developmentally... and their coordination and motor-skills too.
This will also probably happen once she starts to sit-up, pull-up and start to stand. They will do this in the crib too. All normal.
It will also happen whenever the baby/child is hitting new Milestones, too.
Both my kids did that too. All normal.
All the best,
Susan