DocuSign integration - multiple "subaccounts" ?

Summary:

My client has different subaccounts by Business Units, how does the integration and document templates work ?

Content (required):

Hello,

We would like to set up some e-sign tasks using DocuSign : for example a "Sign disclaimers French" for France, and another "Sign disclaimers Spanish" for Spain.

My client currently has multiple DocuSign "sub-accounts" (one per Business Unit) that share the same User ID, but each has their own Account Key (API Account ID in DocuSign wording).

For example, I've first added the french sub-account fine. But then I try to add the spanish one and got this error message :

Since they share the same User ID, I guess it is not possible to add multiple sub-accounts ?