Yes. Even though this is a May-December romance. There will be brood. Platies are very accepting fish and will mate with any other variety or species of Platy
they fancy. They love everybody.
But observe: livebearers have the ability to store sperm from a single mating for many months at least, and have several successive pregnancies as a result of that, even in the absence of male fish.
One female Guppy
I owned years ago had at least five pregnancies without a mature male in sight. Talk about the gift that keeps on giving.
So: even though she may become pregnant, who really is the baby-daddy? The deceased husband or her current Amor?
Alas, only a knowledge of the genetic background of all three fish and the appearance of the baby fish may possibly give you enough information to figure that out. Or it may not. You might have to wait until the babies have babies and see how THEY look, before you know. Ya know?