Affiliated Service group?

[Guest Whatup]

A and B (Husband and Wife) own 100% of D.

They also own 15% of a new entity, B.

SHs of A own the rest of B.

D is going to provide services to B. That's 100% of what they do. So we get that they would be an Affiliated Service Group, preventing D from setting up their own SEP/QP.

But what if D provides all of it's services to A? Will that work? A and B are a controlled group. Is there something in 414(m) that makes me look at the controlled group rather than just entity A? Can D setup their own plan? Would they be an ASG in providing services to A?