This might seems a little bit off but i have been trying to wrap my head around permission, roles and groups. I am new to octobercms and learning by practice and i find your plugin easy to grasp.
I have two groups and two registration forms meant for these two groups, One for sellers and the other for buyers. I want users to be automatically added to groups on registration. I little digging around and i learnt i should create a new plugin and add this in the boot method