Bopanna and Mergea were the last pair to qualify for the event, to be held at the O2 Arena.
They have been drawn in Group Ashe-Smith along with John Peers/Jamie Murray and Simone Bolelli/Fabio Fognini.
The other Group, named Fleming/McEnroe, comprises of Pierre-Hugues Herbert/Nicolas Mahut, Ivan Dodig/Marcelo Melo, Marcin Matkowski/Nenad Zimonjic and Jean-Julien Rojer/Horia.
The top two teams from each group will qualify for the semifinals.
Only the top-8 men's players/pairs qualify to play the year-ending event.