Pass parameters to a custom signup page

Hi,
hope you can help me with this issue.

I have coded a mechanism to generate an individual referral id link that each member receives upon signup, so they can share that link with with their friends and I can keep track of who referred whom in order to grant rewards to the referees.

Initially I built a custom sign-up page reachable with a parametric URL like
https://www.mysite.com/cp-signup?refId=739455 .

OnReady, I read the parameter from the URL.
OnSubmit I store the parameter in a custom collection linking the ReferralID with the ReferreeID.

Now I realized that Wix members Signup has three options:


Default Form (a full page login) → This is not editable in Wix Code
Custom Signup (a full page lightbox) → This is a lightbox
Corvid Signup (a boxed lightbox) → This is a lightbox

Therefore it seemed I was forced to develop a custom signup form in a lightbox, so I had to find a way to pass a parameter to a lightbox. I found it is doable with the openLightbox API .

Fine, but now the point is that a light box does not have a URL itself, so say that a prospect customer receives the invite link with https://www.mysite.com/SIGNUPLIGHTBOX?refId=739455 my understanding is that I cannot expect them to click on the link and land with the open signup lightbox and the parameter refId=739455 already in it.

Hence I thought to create a page, with a proper parametric URL on which an automatic lightbox pops onReady and pass the parameter, but we are back to square one as Wix wants me to put the signup form only in a lightbox.

In conclusion:

  1. Is there a way to invoke directly a lightbox from an external location and pass it a parameter?
    OR
  2. Is there a way to setup a normal page in Wix as a Signup page instead of a lightbox?
    OR
  3. Do you see any other solutions to achieve what I want to do?

Thanks a lot for your help.
Matteo