AI for Customer only when Vendor is Required

For transactions that hit income accounts, we may only want to select a Customer (not a vendor). However, if we need Vendor to be required, is there a way for the AI to be smart enough to know that only one or the other (customer vs vendor) is needed? So, if a customer is selected for an income account, a vendor wouldn't be needed. We'd still like to keep vendor required for all transactions, but for those few income transactions, it's causing confusion for clients. Help please.