Just to clarify - are you wanting an internal door between the rooms? If so, you need to request “CONNECTING rooms”. If you just want them next door or close but with no internal door, THAT is a request for “Adjoining rooms”. Connecting and Adjoining mean very different things in hotel-speak.
Either way it is only a request (regardless of what the phone CM says). You’ll need to call - or have your travel agent call - and put the request on your reservation.
I don't think any of the family suites connect, however there should be Little Mermaid rooms that connect. Make "connecting rooms" your only request, but there is no way to guarantee it.