I found a ticket that had this exact question, but left me searching for a custom Javascript solution. I found a much better solution in the . . . documentation:

Repeater Fields

I'll explain how I made it work below.

I could not find anywhere how to send a calendar invite based on a FF entry, so after working on it for some time I was able to get it to work for me. Hope it helps someone.

Have you ever wanted to know if the unique value of a record you're about to enter is already in the system before you click save? If so, here's a solution for you.