Q:

Angularjs Adal and additional claims or properties for Authorization

Scenario is Angularjs 1.6.5 app with a c# WebApi. Authentication is done against AAD with the use of angular-adal.js. Up to now, everything Works perfectly, as users are able to login through AAD and WebApi accepts the token. 
For this specific app, the roles are in an External application, to which the WebApi has Access. I have been able to add the role claims (after fetching them from the External app) with the use of WindowsAzureActiveDirectoryBearerAuthenticationOptions with the following code inside the ConfigureOAuth(IAppBuilder app): 
app.UseWindowsAzureActiveDirectoryBearerAuthentication(
new WindowsAzureActiveDirectoryBearerAuthenticationOptions
{
   TokenValidationParameters = new System.IdentityModel.Tokens.TokenValidationParameters
   {
       ValidAudience = clientId
   },
   //Audience = ConfigurationManager.AppSettings["ida:ClientID"],
   Tenant = tenant,

   Provider = new OAuthBearerAuthenticationProvider
   {
       OnValidateIdentity = async context =>
     {
         // Retrieve user JWT token from request.
         var authorizationHeader = context.Request.Headers["Authorization"];
         var userJwtToken = authorizationHeader.Substring("Bearer ".Length).Trim();

         // Get current user identity from authentication ticket.
         var authenticationTicket = context.Ticket;
         var identity = authenticationTicket.Identity;

         if (identity.FindFirst(System.Security.Claims.ClaimTypes.Role) == null)
         {
             var user = identity.FindFirst("http://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn").Value;

             Cis.bll.Xrm.bllSystemUserRoles bllSystemUserRoles = new Cis.bll.Xrm.bllSystemUserRoles();
             var su = bllSystemUserRoles.getByEmail(user);
             //var roleClaim = new System.Security.Claims.Claim(System.Security.Claims.ClaimTypes.Role, su.stringRoles);
             foreach (var item in su.Roles)
             {
                 identity.AddClaim(new System.Security.Claims.Claim(System.Security.Claims.ClaimTypes.Role, item.xrmName));
             }
         }
     }
   }
});

So for each httpRequest that Angularjs does to the API, the previous function looks up the roles for the user and adds the role claims. With this implementation, I am able to use an AuthorizeAttribute in the Controller methods, restricting Access to only certain roles like so: 
[CustomAuthorize(Constants.Roles.resourcesAdministrator)]

I find this way highly inneficient, because with each httpRequest, the API has to fetch the roles of the user from the database (or whatever persistance way is implemented).
What I want to do is to read the user roles just once, and then be able to use them in the API with every subsequent request. Is there a way to add the claims to the token AFTER we recieve the token for AAD? 
BTW, I could just add a Roles property to each model, or something like that, but it is not what I'm looking for.
If you have any other ideas or suggestions, they will be greatly appreciated.
Regards

A:

The token is not able to modified since it is issued. And since the roles is stored in the other application, I don't think it is possible to get the roles without query the database.
In this scenario, we can manage the roles though the Azure AD application roles & role claims. Then it will issue the roles claim in the id_token. 
For example, we can modify the manifest of the app like below:
"appRoles": [
    {
      "allowedMemberTypes": [
        "User"
      ],
      "displayName": "Writer",
      "id": "d1c2ade8-98f8-45fd-aa4a-6d06b947c66f",
      "isEnabled": true,
      "description": "Writers Have the ability to create tasks.",
      "value": "Writer"
    },
    {
      "allowedMemberTypes": [
        "User"
      ],
      "displayName": "Observer",
      "id": "fcac0bdb-e45d-4cfc-9733-fbea156da358",
      "isEnabled": true,
      "description": "Observers only have the ability to view tasks and their statuses.",
      "value": "Observer"
    },
    {
      "allowedMemberTypes": [
        "User"
      ],
      "displayName": "Approver",
      "id": "fc803414-3c61-4ebc-a5e5-cd1675c14bbb",
      "isEnabled": true,
      "description": "Approvers have the ability to change the status of tasks.",
      "value": "Approver"
    },
    {
      "allowedMemberTypes": [
        "User"
      ],
      "displayName": "Admin",
      "id": "81e10148-16a8-432a-b86d-ef620c3e48ef",
      "isEnabled": true,
      "description": "Admins can manage roles and perform all task actions.",
      "value": "Admin"
    }
  ],

And assign the roles to the user through the application via Azure portal like figure below:

Then we can get the id_token like request below(implicit grant flow), the roles should be in the token. And we can call the web API using this token.
Get:https://login.microsoftonline.com/{tenant}/oauth2/authorize?response_type=id_token&client_id={clientId}&redirect_uri={redirect_uri}&nonce={nonce}

id_token sample:

