Relational columns

#1

I’m not really sure what the proper title for this question should be.

I have 3 tables. 1 for each client interaction. the table begins with Full Name | Last Name | First Name.

Generally, I will input client names as Last Name | First Name. I want the Full Name column to then autopopulate as “Last Name, First Name”. This part, I managed with the concatenate formula
BUT
there will be times when the client is already in Table 2. In that Case I would like to @FullName that client into Table 1. and have |Full Name|Last Name| autopopulate from the Table 1 row (as well as other attributes like client Number.