Mange multiple apps using MS Graph

Hi,

Pre Infor:

I have multiple apps in azure. Instead of managing users for these apps in the azure portal, I am planning to create a separate app (User Management Tool). This app also has AD authentications. Once the user completes the success login. 

Admin needs to manage the user in all apps, like adding users to the app, updating roles.  

Problem:

Not able to connect to multiple apps with tenantId, ClientID, Secret Key. Not able to get the token for these apps using client secret. 

Please guide me way to handle this

Thanks in advance