You first need to go to the group where you want to add a new member and then click button “Add new member”:
Fill in all the mandatory data on the opened modal “Add a member to the partner group”: email address, name and surname, phone number, role (admin or employee). Click “Save” to keep changes.
Admin role allows users to make changes in the company. Employee role allows to only view the company details.
Role of the member will be relevant not only for all the companies in the group, but for all companies in subgroups too.