Multiple OVRInteractionComprehensive building blocks in project

I'm using the OVRInteractionComprehensive building block as the basis of my project with a distance grab block. I then added the HandPose Features to use 2 preset hand poses (Rock and stop) and this automatically added a second OVRInteractionComprehensive block to manage these poses.

I've now added a basic menu but can't get either ray interaction or poke interaction to function on the menu buttons. It seems the previous two blocks already in use in the project are blocking the event system from working. When I add a canvas it won't add an event system.

Can anyone suggest the best way forwards and point me at a tutorial that might help. Thanks!