There may be instances where one user administers, or is a team member of, more than one business. In this case, the user can access multiple accounts with their unique login.
In order to give the user access to your account, simply ensure they have one common user name and password that they use for all businesses they are associated with, then invite them to join your particular business. You can set their access rights to Admin or Standard Access in your business.
Go to Settings > Team members
Select '+Add' in the top right
Complete their information, and invite them to your business