User access within main site and one subsite

Silverstripe Version: 4.3.3

User access within main site and one subsite

_We have a main site and multiple subsites. I’m wanting to give a user on subsite 1 certain permissions, as well as certain permissions on the main site. However to do this I would assume I’d assign the user to a group in subsite 1 with only access to that subsite, aswell as being assigned to a group on the main site. However I can only choose ‘All subsites’ within a group to give them access to the main site, but that gives access to all subsites’. Am I missing something here? _