Linking two pre-existing tables via a drop-down menu
I'm constructing a database for our counseling agency that has two tables: Clients and Therapists. As I create a record for a client, I want to be able to link them to their associated therapist, and would like to be able to do this utilizing some sort of drop down list of currently existing therapists. The difficulty that I'm encountering at this point is that when I place the "Therapist" field in the portal (based on a value list that pulls from a name calculation field in Therapists), I can't access it unless "Allow creation of records in this table via this relationship" is checked, but when it is I create a new Therapist record every time, as opposed to just selecting one that's already there.
Additionally, it would be FABULOUS if I could have a system that allowed the user to type in the first letter of the therapist's name and have it scroll down to that area (on the drop down menu or whatever), as we have quite a few therapists and the list is rather long to scroll through by hand.
Help! And thanks!