I have a non-profit client that this opening a kind of "branch" organization. The second organization will have it's own site with it's own URL, but they would like to keep the same theme for both sites, but with a different color scheme.
There will be shared content on both sites, but most pages will be at least a little different. The "About" page will be similar, but on the new site, there will be information about the original organization AND information specific to the new "branch."
My initial gut instinct was to port the Domain Acess module for this project. BUT, the more I think about it, Domain Access might not be a good option if the content is similar but not the same. Both sites will have a page at /about, but the content will not be exactly the same and the paths will conflict. I don't think Domain Acess is good in this scenario. Domain access would be great if pages with the same path had the exact same content.
I've never really used Multi-Site before, but maybe it's the better solution here. Although, I'm not sure if it's that much better than just building two independent sites.
What advice do folks have?
NOTE: Domain access is a suite of modules for Drupal that allows one to build multiple sites using a single database and share content amoungst the different sites. It has not yet been ported to Backdrop CMS, but there has been strong interest in completing that port.
SSO was provided by another company, the module that is used on D7 is OpenID Connect (openid_connect) with OAuth authentication and Real Name module.