MercerJon:
The above code works perfectly when the referenced model hasn't moved
I don't understand that statement. If nothing moved, what worked perfectly?
Master and Reference Origin
Those are read-only properties of an Attachment. You can't change them.
The process you need to implement is...
- Gather information about an Attachment that you want to persist
- Detach that attachment
- Reattach the model using a new location and your saved data (if any). That is, you create a new Attachment