It sounds like you have a many to one mapping which can't work. Something like this
Site A Site B
RP 1 > RP A
RP 2 > RP A
In this situation, there is no way to reverse the second mapping because you would end up having A mapped to 2 things (RP 1 & 2) and SRM wouldn't know what VMs to put where.
Does that make sense?
Yeah, I think so.
I ended up creating RP1 - RP5 under the SRM resource pool in the recovery environment, and created the mappings as 1 to 1, which worked a treat.