{Original Answer} No, you cannot add or edit members (in the registry) on a project that receives it's registration from another project (Auxiliary projects and most back translations). If the back translation has it's own registration, it should appear in the registry.
{Response from questioner} So is there any way for Paratext organisation admins to add people to a back translation or auxiliary project, which is registered under a standard project? We are concerned that if the administrator of the back translation or auxiliary project stops working or passes away, our organisation will lose access to that information. At the moment, we can't see/edit the member list of these projects in the registry, and we (as organisation admins) can't add ourselves to the projects in order to see them in Paratext. Or if we are already on the BT/aux project as observers, we can't change our role to administrators, so still can't add new users. The system for standard projects, where we can see/edit the member list in the registry, and add ourselves as admins is great. But we really need this ability for projects which are registered under the standard project too.
{Second Answer} I would recommend that you make sure your role is updated to Consultant on your projects so that if needed you can temporarily act as an Administrator. However, as to the issue of being able to do this in the registry, I would suggest you use the Help > Give Feedback in Paratext to make this a feature request.
