Yeah. you should probably just leave her in the main the tank. You'll have so many that it's not worth stressing the poor girl guppy by putting her in the breeding tank. Just keep scooping the babies out.
These mommy fish spend their lives being chased by males, getting pregnant, growing fat, having babies and the cycle just cotinues on a monthly basis. Poor things--we shouldn't take them out of their homes and put them in breeding tanks if we don't have to.
I mean with guppies and platies--these fry come nonstop no matter where they're born. Put the babies in a separate tank if you don't want them to be eaten. Some people even say that if your tank is big enough and has enough plants and hiding spots that you can just leave the babies in there--survival of the fittest. My tank is a 10gallon so I take them out because my zebra danios are always on the hunt.
"It is a poverty to decide that a child must die so that you may live as you wish."