Document sequencing for Invoice numbers in Receivables

Hello,

I was wondering if any of you have implemented a document sequencing for Invoice numbers in Receivables. We are using Lease Management, so the transaction type for Invoice import is a seeded value "OKL_CONTRACTS" . We have two Operating units, both going into the same Ledger, and each of them will prefer to start the sequence with a different number.

When it comes to defining a document Category, I can only define it once, for a combination of Appication and Ledger. So in this example,  Receivables, OKL CONTRACTS and Ledger name. This will work for one OU, but when it comes to the next OU, I cannot use OKL CONTRACTS again, as it violates the unique combination of category code, application and Leger.