DPub Roles 2.0 as joint deliverable?

With the merger of the IDPF with W3C and influx of W3C Members 
interested in digital publishing, a Digital Publishing Working Group is 
being proposed. One deliverable would be a 2.0 version of Digital 
Publishing ARIA Module (the ARIA WG currently has the 1.0 version in 
CR), and the question has come up whether the ARIA WG prefers that be a 
joint deliverable or just a deliverable of the new DPub WG. Does anybody 
have opinions on that question? Michael