My process generates an automatic letter to the user within a single entity. You need to add a field value from another related entity to the letter. Please help me how to do this?
Entity 1 - Opportunity; Entity 2 - Organization to which the opportunity belongs.
Unlike other activities (Email, Appointment, etc), Letter is a different concept. It won’t generate a document, it is simply a note or task as a placeholder to generate Letter using Letter template (Mail merge in old days) - so respective Person can generate it in CRM UI, print it and send it offline. Read more
That being said, you can generate a word template with any parent and it’s related entities, compose and save it for later use like Letter use case. Read more