Hello Jeanne and Amritendu,
Thank you for your replies. Actually I searched the forums here for my doubt (without specifics of course) and I found this answer by Fernando
here. I feel this comes closest to the ambiguity I am facing. It is basically a domain model cardinality problem.
It comes down to this - You can either be true to the domain model or the use-case. I think, in such a scenario, an assumption (which as you said should NOT oversimplify the problem) is acceptable and should help.
Thank you again for replies and please feel free to add anything.
aditya