Huh? With the A/P engaged the PF is the one responsible for all selections on the FCU/MCP as he's the one flying the Aircraft and knows what he wants it to do, how and when.......surely??
Obviously with the A/P off the PM makes the Alt selection without direction BUT all other changes are directed by the PF.
I don't like the idea of both seats making changes on the FCU/MCP at the same time!!