Event Info page should provide relative link to event registration page

The Event Info page currently displays an absolute link to the Event Registration page (for events with online registration).

Since the event registration page should always be accessible from the same URL as the event info page, this seems like it should be a relative link instead.

We have many groups that operate under two different domain names - one domain is for the C3 (tax deductible charity) and other works is performed under their c4 (can do political organizing).

We have configured our web server to work properly with both domains.

They want to be able to advertise events for both groups. So, for c4 events, they send people to the event info page using the c4 domain. For c3 events, they send people to the event info page for the c3 domain.

However, with absolute links, the event registration page always shows the URL/domain of the default setting.

The only reason I can think of for using an absolute link is if you are somehow only using https on the registration page, but http on the info page. But not even sure that is possible.