bonding on top of easifill?

[redhexagonal]

I’m replastering a stair winder, having hacked off some bits and built up other areas with bonding, there are some areas that I initially used easifill on that I’d like to add another inch or so to. Can I apply bonding over the easifill, or should just build up easifill layers slowly? Or should I hack off the easifill and start over again with bonding?

 

[Lower]

I'd gouge out most of the easyfil, bond onto whatever is solid underneath, and then easyfil over the top.

Easyfil isn't very strong so i'd be nervous of using it as a substrate for bonding.