@juliesgarden they are tricky to overwinter here...you can either make them go dormant or I keep mine going under grow-lights in the polytunnel. I've been growing a small collection for a few years now.
@brightcolours never grafted to them....prob quite straightforward. I'm just happy I can get the cuttings to root and grow! All my plumerias I've rooted and make their soil from scratch to stop any water rotting the roots.