How to use Event type from PPM in Receivables SLA

Our requirement is to generate different types of invoices (like proforma, Advance, Final) . But as there is the limitation that we can have only one transaction type on a contract.

We are planning to use different event types for these invoices generations, our requirement is to derive different accounts based on those event types.

Is there any way to use Event types or any parameters on receivables SLA?