No User / Same Function

I have a unique situation. I need 2 roles enabled on sign up. There is another plugin that worked perfectly allowing me to add secondary roles; however I had to add it to each individual user. That would be a large inconvenience for myself and my users. Is there any way I can set by default 2 roles at a time for all? I’m using a membership plugin that unfortunately has everyone set as subscriber. I need subscriber and seller features.

https://www.ads-software.com/plugins/role-includer/