Hi Jamie, one possible solution may be to have the two sites share the same user and usermeta tables. So if a user registers on one installation they would be able to access the other.
I found a description of this at https://www.remicorson.com/share-users-database-on-different-wordpress-installs/ (you may get a security notice when you go to this site). I can’t speak to how well this solution would play with a membership plugin; you’ll want to be sure that if you make a person an Administrator on one site, for instance, that they don’t end up being an Administrator on both.
Another possible approach would be to use custom programming that would copy the user data from the site they registered on to the user tables on the second site, but you would need to determine to what extent this data needs to be synchronized so it’s identical on both sites at all times.
Since multisite is not a possible solution for you, you may want to take this to the Advanced Topics forum rather than the Multisite forum. Depending on your level of experience with MySQL, PHP and so forth, you may need someone who can write the necessary custom code for you.
@jamiesw
I just wanted to chime in real fast and mention that what you are looking to do is called Single Sign On. There is many ways to achieve Single Sign On but the main way is going to be making your main WP site an OAuth provider.
Once you main site is setup, you can have your other WP site link to your main site using OAuth/OAuth2 workflow. This process uses access tokens and is secure. Do a simple search in the plugins for an OAuth Provider and you should see plugins that will help you in your journey.
Hope this helps!
Hi Susan\Justin,
thanks for the advice. I did think about using triggers in mysql to copy the data from one to another, will look at OAuth as a possiblity as well.
Thanks again.