It is commonplace to have a single Office 365 tenant that hosts multiple schools. This makes it easier to manage in one place and cuts down on the administration. If you want to restrict which schools can login to SchoolWise and use the Office 365 functionality you can do this from the Azure portal.
Go to https://portal.azure.com and login with a global administrator account for the tenant
Click on the Azure Active Directory menu option on the left bar
Click on Enterprise Applications on the blade
Then click on All Applications on the next blade
On the list of applications scroll down until you see SchoolWise and then click on the application to view its properties
6. Click on the Users and groups button to display the blade
7. Then click on the Add user button to bring up the list of users and groups
8. Click on the Users and groups selector to bring up all the users and groups in your tenant. Use the search box to select the all the users or the group you setup where all the users are members.
9. Click the Select button at the bottom of the screen
10. Click the Assign button at the bottom of the Add Assignment blade to apply the changes.
Now only those users or groups selected will be able to login and use the Office 365 functionality of SchoolWise.
Note: It is best practice to add your users to a group and then assign the group in the Azure portal to the SchoolWise application. This way you can add/remove users from the group without having to update permissions to the application each time. You can select multiple groups in the selection if you want to authorise more than one school.