Client requires the currency in Sales Order UI to be updated based on the contract currency

Summary:

The current setup is to default the currency based on the Business Unit selected(done through pretransformation rule with input BU and output currency values).

Now the below change needs to be done: 

The client has contracts(under Manage Contracts - for eg: Contract Number=2000) with the customer and contracts has contract currency associated to it. The Bill to Account value(for Customer X , Bill to Account=2000) is same as the contract number. So whenever the customer is selected and Bill to account chosen, we would want the currency field in Order Management Create Order UI to populate the contract currency if it different from Business Unit Currency. Can this be achieved in Oracle Fusion Order Management?