If some of your customers are not shown in your reseller Partner Center account you can follow this guide to link them.

  1. Logon to your Indirect Reseller account on https://partner.microsoft.com Select Customers from your Partner Center menu and then select Request a reseller relationship.

  2. To request administrator permissions from this customer, select Include delegated administration privileges for Azure Active Directory and Office 365. To establish the relationship without requesting administrator permissions, clear this option. Send the email to your customer.

  3. Open a different web browser or private browser window and open the
    invitation URL mentioned in the E-mail notification. Logon to the Customer tenant using an account with Global Admin privileges. Now accept the Terms and agreement by checking the box. Press the Accept and Authorize button to grant permission to the reseller on the customer tenant account.


  4. Now the customer is linked to your reseller account and will be shown in your Indirect Reseller account on the Partner Center. You now also have the permissions to single sign-on to the customer environment. All future customers that place new orders through the 2tCloud Platform will automatically authorize you as a reseller.

 

Full details in Microsoft guide:
https://docs.microsoft.com/en-us/partner-center/request-a-relationship-with-a-customer#invite-a-customer-to-establish-a-reseller-relationship-with-you