It's very important to get the wrong members off the team. Have a firm wide policy on who gets to go to the beauty contests. Involve the firm's management in the decision. Ask the managing partner to have the wrong lawyer step aside. If you can't get the wrong lawyer off the team, let him play master of ceremonies.
Rehearsals are essential.
Make sure that everyone on the team reads the firm's proposal. Use e-mail to organize the team, particularly answers to questions the client will ask, questions the team will ask to create dialog and a role for each team member. We are all fragile creatures. During the coaching, marketers should value each person's strengths. Emphasize that if the work is worth getting, it's worth rehearsing for.