Hello all, 

I have been working on the feature mentioned in: 
Bug 911515 - RFE: Allow installation of distros which are not imported in beakerand have written a proposal [1] about the functionality.
Please feel free to read the document and leave your feedback in here or in the bugzilla [2].

[1] https://beaker-project.org/dev/proposals/allow-installation-user-defined-distro.html 
[2] https://bugzilla.redhat.com/show_bug.cgi?id=911515

Thanking you,

Anwesha Chatterjee
Software Engineer
Red Hat - Brisbane