We wouldn't be sourcing and contracting them, they would. We would hold the contract, pay them as PMs and they would pocket the difference. They get the premium of subcontracting with out holding the risk it seems. It might be fine and they were the cheapest but we don't know enough to make a good judgment so we wont be using them.
An important thing to ask is who will be taking the design responsibility of the project because looking over what you've said recently it seems like that's what they're trying to avoid. Although it may go to the project management side but its definitely always good to ask to avoid doubt.
We wouldn't be sourcing and contracting them, they would. We would hold the contract, pay them as PMs and they would pocket the difference. They get the premium of subcontracting with out holding the risk it seems. It might be fine and they were the cheapest but we don't know enough to make a good judgment so we wont be using them.