My first post on this board, so please no flaming

I am travelling with my wife and 2 daughters before Xmas BKK-DXB-JFK-DXB-BKK in C .
My travel agent through which we bought the tickets messed up the seat selection on the JFK-DXB flight ( other sectors are fine) and we end up all seating in different rows and I am really worried about my 2 daughters ( 8 and 12) seating next to complete strangers for over 12 hours.
My travel agent has sent a special request to EK to change seats so we can be somewhat together, but since the flight is fully booked there is no change so far .
Don't know what else to do , so your suggestions would be highly appreciated.