Ok the name of my report is "FieldService_WorkOrder_ToddCo(4)". This is the Print Template I am customizing for our Work Orders in the Field Services App. I have selected it as the Default Work Order Template (Print). I am viewing the report from the Add / Edit Work Order screen by clicking the Activities button, then Print Work Order.
To answer your other questions:
1. I copied FieldService_WorkOrder
2. The master table is "Activity". The detail tables are "ActivityJobItems.ActivityNoRef" and "Customer.ActivityRef". The master and the first detail table are the default. The Customer.ActivityRef table is one that I added after I created a linked field. See below.
3. First I created a dropdown in the Activity table called "Customers" that links to the RecordID in the Customer table. Next, because I wasn't sure if that was all I needed to do to create the relationship, I created a dropdown in the Customer table called "Activity" that links to the Record ID in the Activity table. This may be redundant, so if we need to delete one or the other just let me know. Finally, I created a linked field in the Activity table called "County" using the County field in the Customer table. This is the one that I am trying to display in my Work Order template (there are others, but I can repeat the process once we get the first one working).
To summarize, what I am trying to do here is display fields from the Customer table in my Work Order and have that info print (i.e. "County").