.NET Core Application and Azure

We have developed an application in .NET Core using Visual Studio 2019. This application is relatively simple; when a user opens a “proprietary” Excel workbook (an Excel file that calls our code) the application goes out to a hosted (by us) Azure SQL Managed database and returns data based on the parameters passed in by the user.

In Azure, we have a single production App Service plan with an App Service dedicated to each client (company). My question is about security: I’d like to tie each App Service to the related company’s Azure AD. I do NOT want to create an account on my Azure AD for each user, although I can certainly do this through the “invitation” process using B2B. Can each App Service be “pointed” to a specific external instance of Azure AD so that only users from that company can access the related data? B2C doesn’t seem to provide this functionality.