Merging Photos with Photostream

Hello everyone,

I have a quick question. If someone has two iPhones with images on them, one has Photostream enabled and the other one doesn't (but has images locally stored on the phone), does Photostream "sync" the images?

I'm setting up a new iPhone for someone. The new phone has local images stored on it without iCloud enabled, the old one does have PhotoStream enabled with images. I just want to make sure that when I enable Photostream on her new phone that her images will carry over and that her local images will also upload so that everything merges together.

Any help greatly appreciated!