M.M.
All formula here is FDA regulated, so it's all the same.
At 13mos, her little digestive system is doing just fine, so a direct switch won't affect her.
(I've switched my kids at 6mos to cheap brands. No issues at that point.)
She may balk at the taste, if she's picky. But healthwise, there's no reason to not make a cold switch.
PS: my kids were off formula completely at 1yr. The doc had me put them on whole milk, instead.