Executives close to BMW say the carmaker is contacting other agencies about their media buying capabilities.
Executives at BMW said there are no problems with their relationship with DeWitt, adding that there were meetings last week to discuss future projects.
Fallon McElligott, Minneapolis, handles creative for BMW.
DeWitt CEO-President Gene DeWitt declined to comment about BMW, but did elaborate on his shop's partnership with the Berlin shop, whose principals have automotive experience.
Mr. DeWitt said the new agency and DeWitt, both New York, will jointly seek out and pitch new business.
The two shops also will join forces to work on current Berlin client Beth Israel Medical Center. But Mr. DeWitt said they will approach other current clients about using both parties with caution.
"We're going to tread gingerly here. We don't want to create conflicts or confusion," he said.
Berlin clients include Coca-Cola Co., Conde Nast Publications, the National Basketball Association, NBC's Olympic Games and The Washington Post. DeWitt clients include Discovery Channel, RiteAid Corp. and ServiceMaster Corp.
OFFERING FULL SERVICES
The joint plan "is strategic and in the best interests of both organizations," said ad agency Chairman Andy Berlin. "It benefits us because we can offer our clients full services."
Although the two shops will exclusively pitch new business together, DeWitt still will work with creative shops of its current media-only clients.
Mr. Berlin launched his new agency this month after negotiations with Fallon Chairman-CEO Pat Fallon to buy Fallon McElligott Berlin fell through.