Multiple Connections with Authorization with email and password through token request

I have a question related to this question. How to authorize user with email/password from server code? - Auth0 Community
I am looking to setup an enterprise (ADFS) connection along with the database connection through Auth0. However, when I make a call I have to set the default connection. How do you handle multiple connections? what is the best way to go about doing this?

It seems to work with the Authentication API Debugger because I can specify a connection name. However, it does not let me do this on the call.
https://subdomainname.auth0.com/oauth/token

As part of one of the answers to the linked question a suggestion was made to use an alternative grant type very similar to password but that does allow to be specific about the connection on the request body itself.

As an alternative, if you read further on the ROPC docs you’ll find that the endpoint supports an additional grant where you can specific the connection to be used in the request body itself using the realm parameter name. See:

Call Your API Using Resource Owner Password Flow

Thank you very much. I was able to get this to work with multiple connections. One other quick question about this. Is there any disadvantage of using the grant? It seems like you have to include the client secret.

Thanks!

Actually, it looks like it does not need the client secret. Any other disadvantages to using this way? Thanks!