7.5 - Organizational group security permissions

Can someone point me in the direction of what permission needs to be added to allow helpdesk techs to add computers to organizational groups?

I assume security role manager is right place to do it - is it resources - highlight the organization group - then write permissions? or write resource data?  or am I in the wrong place entirely?

This was working for techs before I had to redo permissions post 7.5 upgrade.  

Thanks for any tips as always