Allow "Connection" field to be a text field

Currently when you have a connector field you can only show a select box or checkboxes.

It would be great if you are able to have a plain text field. If the matching record is found it should be connected, if not, a new record should be created. (Or you should then be able to conditionally insert a new record using the "Record Rules" options.)

An example use case:

I have a CONTACTS table that is already populated with data about my contacts. I also have an EVENT REGISTRATIONS table and a event registration form.

My users complete the event registration form without logging in. The email they enter on the form is used to connect the event registration record to their contact record (if they have one) If not, it is created...

Currently I cannot do this because users see a "Select" box with all other contacts in the email database..