I'm not sure this is possible, but is it possible to use GAM or GAMADV-X to add a shared drive folder to a users "My Drive", basically preforming the right-click and "Add to My Drive" for a user?
We have a few folders that are shared with groups so when a new person is added to the group those folders don't show up in the shared with me section. So my current solution is to upload a pdf to their drive with click this link to go to your folder then right-click and "Add to My Drive". If possible I'd like to just have that folder added to the users drive without them needing to do anything. But since shared folders added to My Drive don't show under gam <user> show filetree, I don't have much hope.