A public registration form is the right door for a conference, a concert, or a school open day. It is the wrong door for a sponsor, a partner, or a guest the organizer invited by name.
When everyone uses one form, two things happen. Sponsors fill in fields written for the general public, and the public can land on an invitation that was meant to stay private. The list you export then mixes people who bought a ticket with people who were hosted.
Split the paths
The public page collects the people who found you: name, contact, ticket or session, and whatever else the form asks. They get a confirmation and a code for the door.
Sponsors, partners, and VIPs get their own list and a private invitation. You already know who they are. You need their response, their tier, and sometimes the amount attached to the partnership — not another copy of the public form.
On the day, both groups still check in the same way. One desk, one scan, one count. The difference is how they were asked to come, and how they show up in the report afterwards.
The room can still be one room. The invitation should not be one form.