Excellent question.
The short answer is no - at this time, this is not a certified and supported use case.
You can use new versions of Business Monitor with older versions of WPS (now called Business Process Manager). But you can not do the reverse.
The primary rationale is that Business Monitor and WPS have tight integration. So when WPS changes, the event contract needs to be updated.
Please do work through your IBM account representative to formalize this requirement. It is important to understand more of the context and frequency of this situation.
Thank you
Eric Wayne