It's possible, but for maintenance simplicity with having same files you should also have same Joomla core database tables, check last two case studies here: https://alterbrains.com/joomla-extensions/administration/multisites-manager/case-studies In other words, it's single Joomla website which ...

That is if you have second domain, if not canonical links are not presented at all - but they should be or they should use 301 redirect.

The solution would be probably same like in previous case. I will try to test it on some new joomla installation.

... can be configured to allow submit for one of these specific usergroups only via usual Joomla ACL. For one Joomla installation I recommend last two case studies: https://alterbrains.com/joomla-extensions/administration/multisites-manager/case-studies

phpBB code is executed inside Joomla code, Joomla-phpBB users are mapped via case-insensitive username.

Please first select the case study you will use:
https://alterbrains.com/joomla-extensio ... se-studies

MightySites can allow all sites to share certain database tables, all users tables should be shared in your case: all slave sites will load users tables from database of master site, hence all users/usergroups/user-usergroup relations will be always same across all sites, no ...

Please check our case studies first: https://alterbrains.com/joomla-extensions/administration/multisites-manager Unfortunately, full understanding of setting up Joomla multi-sites environment requires at least basic developer knowledge ...

Domain B will be slave in this case because it will load K2 and Joomla users from database of master site Domain A.
Both sites will use same tables, so all K2 database data and users will be same on both sites.

Note that K2 images won't be shared if each site uses own Joomla installation.

MightySites doesn't sync database data. It allows to share tables.

In your case 3 sites can use jomsocial and users tables of master site, so these data will be always same on 3 sites: 3 sites with same users and same JomSocial database data.

... If this is an extension - please email it to alterbrains@gmail.com, we need to explore it first. How is your logo configured? Please check these case study - it can be for you: all sites have same data except few database tables: https://alterbrains.com/joomla-extensions/administration/multisites-manager/case-studies/subsites-with-major-differences-in-menu-items-and-or-modules