Parents have booked with Virgin Atlantic. EDI-MCO (Upper with VA) but return flight is with Delta. MCO-JFK (First Class) then JFK-EDI (Delta One)

I know they will definitely get lounge access at JFK with their Delta One boarding card but my question is will they qualify for lounge access at MCO? I checked the Delta website and the wording is very ambigious...........

"Customers travelling on Delta One on an international Delta flight or on a domestic flight connecting to/from a same day international Delta One Flight"

so does their domestic first class flight MCO-JFK qualify for lounge entry at MCO because they are connecting to a Delta One in JFK? Asked on twitter and the agents were none the wiser and google is not being my friend today. Appreciate your advice.