I need to display certain subscribe button based on custom field entry from step 1 of registration p

Hi,

I have added numerous custom fields to step 1 of my registration process using my own add-on.

One of the fields is a checkbox on step 1 of the registration process that relates to a certain membership level (See checkbox on bottom of first screenshot for Affiliate Membership). I then want in step 2 to only display the Normal/Affiliate membership Subscribe button depending on this 'Affiliate Member' checkbox form value(See second screenshot). Does anyone know the best way (where I do not have to amend the core plugin code if possible) so that I can achieve this?

Many thanks,

Al