Because paypal ipn has just plain stopped working even though all settings and permissions are correct, I set up the paypalpro api to see if that's functioning better.
Since that collects credit card information, I want to utilize ssl. However, register lives in an addon domain, so on it's own, the ssl plugin just shunts the page to the home page of the primary domain.
I know that addons can use the primary domain ssl certificate, but the url has to be either addon.primary.com/page or primary.com/addon/page
I know I can set wild card redirects in cpanel, but I want to make certain I do it correctlly.
how do I set up proper redirects so that dt register can use ssl?
An SSL certificate is very specific. It will work for "domain.com" or "addon.domain.com" but not both. Also specific with or without the "www". You can get your certificate for "addon.domain.com" and do any necessary redirects in your .htaccess file to make sure the site is loaded in that url configuration.
You can also get a wildcard SSL certificate (GoDaddy lists them as "Multiple Domains", supports up to 5 domain variations in one certificate for only $90/year). Then you won't have to worry so much about your various url combos.
Then when you have SSL working correctly for your domain, install and enable our SSL plugin, which will force DT Register form pages to use the secure URL.