Update forecast on Revenue Line Item when stage change triggered by Customer Journey BPM

Hi everyone

Background:

I have set up a customer journey on opportunities that maps a user through various stages of our sales process via the completion of tasks. After completion of certain percentages of the journey, I have a BPM that updates the sales stage of RLIs linked to the opportunity. This seems to work well - the sales stage updates appropriately. However, the forecast value on the RLI does not get updated to the relevant "Include", "Upside" or "Exclude" mapped to the sales stage percentages, only when the RLI sales stage is updated to "closed won". These only update when a user manually updates the sales stage against the RLI.

It seems the customer journey updates the RLI via a server side change, but the mapping to the forecast relies on a client side (javascript) change. Hence, the customer journey doesn't update the forecast value. Additionally, the BPM doesn't allow me to change the forecast value, as this is not an option on the form.

Any ideas how I can update the forecast value on the RLI via a Customer Journey BPM please?

Thanks in advance

Ray