Purchase Orders linked to a Project to follow approvals based on the cumulative document amount

Hi,

We have below use case and checking if anyone can please provide some inputs here…

POs created with 'Project' should be routed for approvals when the cumulative document amount exceeds threshold of 1M USD.
E.g. PO1 with Project#123 against Staples for 500K => auto approve
PO2 with Project#123 against Grainger for 300K => auto approve
PO3 with Project#123 against CDW for 250K => should be routed for approval, bcos cumulative amount against Project#123 is exceeding 1M USD.

Thanks,

Bala