The “Source” column is a person’s name.  I’ve discovered I may not have just one source, but can have an undetermined number of sources and their roles.  How can I indicate that in the formula?  I would like the formula to say:  format the first Source & role as follows:  John Smith (Donor) and if there is more than one source & their roles formulate subsequent source/roles in the same manner as the first source/role AND concatenate the subsequent source/roles with a comma and a space as follows: 
Gregory Holt (Donor), Ami Whitus (Agent), John Maxwell (Executor) [and so on]