I can't seem to link a bill to a "potential" the same way i can an expense.

If i'm just missing it, someone please help me out; otherwise, Zoho PLEASE add this as a feature asap!

(for example, we provide "service a".  sometimes a client wants service a and b.  Other company provides service b and sends us an invoice to pay. Client pays us for service a and b.  I need to attach the invoice  for service b to that potential/deal, but it needs to be a bill b/c it isn't paid yet. We can't be the only ones with this problem)

Thanks