How to setup 2 Data Sources in a Enterprise Gateway connecting to same server or database?

Thanks for the solution v-piga-msft Cherry! But, If I add the user to the existing data source User List, won't that user have the same DB permissions as other users?

For example:
User 1 who is already in the User List (from my example - under "Data Source1" and "Gateway1") has DB Level permissions to say 3 schemas.
Server1
 Schema1          Schema2               Schema3
  Table1.1            Table2.1                   Table3.1
  Table1.2            Table2.2                   Table3.2
  Table1.3            Table2.3                   Table3.3

Let us assume that if I add the 'new user' to the same "Data Source1" and "Gateway1" User List.
Does this 'new user' have the same DB Level permissions (access to those same 3 schemas) as User 1?

If so, I do not want this 'new user' to assign that permission. Instead the 'new user' needs access to just 1 schema.
Server1
 Schema1
  Table1.1
  Table1.2
  Table1.3

So, when I use a Service Active Directory account, I assign this service account to the requested schema's with read permissions.

Basically, when a add the 'new user' to the User list, that 'new user' should not see the Schema2 and Schem3.

How should I go about configuring this in the Gateway? Any other alternatives? Thanks!