The last time I was at any interfaith event, is what spoiled Orthodoxy for me. I could not believe what I saw.
Hopefully this one would be better. St. Seraphim's in Dallas (OCA) or Holy Trinity Greek Orthodox in Dallas may send somebody.
There is also a EO convent in Kemp, TX.
Milan in Austin.
Also there is a Romanian Church in Dallas, Antiochian, and other Greek churches.
There is also a ROCOR parish in McKinney TX where the priest would probably be interested in going. That church is St. Nicholas Orthodox Church. He has a great domain name, orthodox.net - somebody may want to give him a call and see if he'd go.