Connection setup and Live app for multiple user roles updating common table

About connections: I’m trying to create build a student application form for prospective parents, and current parents of our program. I have a new user role, Prospects, to go with pre-existing Parent role. I have a Household Info table (contents of application). Email is the common field across Account (Parent and Prospects), & Household Info. I have tried endlessly to set up connections and login Live App page so that someone can signup (Prospects) and have Knack recognize that login email, create an initial record in Household Info, with that email to Household Info > Email field.

Even after reviewing Help everywhere, I cannot get Knack to show email on login after sign up on the application form. I would like users to not have to retype email to signup, login, fill in the form.

For existing parent with logins, can I set up the Live App to cue off either Prospect or Parent roles, or only one role per user role? As it stands, even tho there are references to “This form updates a NewScholarApplicationHousehold record connected to the logged-in Prospect.” on my form, my email field is either blank or presents a dropdown list of all Prospect role emails for all records in that table. Guidance is much appreciated. Really. Thanks, Sara