With Google+ and most Google products, you can set it up to allow multiple sign in with Google accounts.
Below are steps on how to do this:
1. Sign in to your Google+ account
2. Click on your name, at the top right hand side, for the drop down menu
3. Select the “Account Settings” option
4. Under the “Account Overview” section, you will see a “Multiple sign-in” selection. Click on the “Edit” link.
5. Turn the feature on by clicking on the “On – Use multiple Google Accounts in the same web browser” and check all the checkboxes
6. Click on the “Save” button to save option