Why are they entering the rep email as opposed to the lead email? Use a separate custom field for the partner email?
You should move this to Products (Move link at the right) as it's extremely Marketo-specific, ("Central" is for general marketing discush.)
As Chris says, one would expect the rep (referrer) to be entering their own address only once and then also add the email addresses for the leads (referrals),
In any case, as you'll see in other posts, you want the Referral Form pattern. It's a relatively simple setup and will result, in your example, in 3 new leads being created, as well as a Filled Out Form activity for the rep (reflecting their most recent referral(s)). A JS developer who understands the Marketo Forms API can build this for you.