GPO pricing - multiple contracts to one customer

We have a situation where 1 Customer (Sold To) may have many Contracts. Our current SAP setup allows for only 2 pricing conditions to be linked to a sold to at one time. One Customer order may draw from 3 separate contracts. How can we make all contracts active and accessible for correct pricing retrieval? We encounter manual workarounds and pricing failures when processing orders via EDI and orders go to incomplete status due to pricing discrepancies.