Apologies for the delayed response.
If you are looking to add the same user to multiple Customer accounts, you can add the user in the MSP account
and associate it to different customers as per your requirement.
However, if you are creating a user for individual customer account/portals
, you might be adding different end-customers in their respective accounts which has to be done at the Customer level as those users are specific to Customer accounts and not MSP account
. However, we have extended the possibility of adding individual users under Customer Accounts with different roles for which you can refer this article
If it's the same user that you are adding into multiple Customer accounts, we would suggest you to add that user under the MSP account and associate them to different customers, so that you can create just one authtoken and use it for different Customer accounts for which you can refer this API doc