Database engine that share a row among multiple tables
Isn't this what CASCADE option on foreign key is supposed to do? You can find that in many DB engines.
It is not ok to perform the join on Fullname column as long as you have a CID column, which is supposed to be the identity. It is just a bad practice, and can have undesired effects - like the one you encountered.


In conclusion, either you change the joining column, or try to active the cascading on update capabilities of your DBMS.