The problems are £5 million of Heinz frozen food business, which is a potential clash with JWT's Kraft and Nestle assignments, and the Nouvelle toilet tissue brand, which could not sit alongside JWT's Andrex account.
Client and agency representatives are trying to find a way around the difficulties, which follow last week's successful offer by JWT's WPP parent for Cordiant, which owns the Bates network.
One possible way out could be to put Heinz into the Manchester-based Cheetham Bell JWT. Nouvelle could be retained if its Georgia-Pacific owner agreed to move to WPP's HHCL/Red Cell.
HHCL is already in line to pick up the entire Sky TV account it shares with Bates.
Other Bates business set for JWT includes the £8 million Roche business, including the Rennie and Sanatogen briefs, and Pfizer, whose £5 million-worth of assignments include Benylin and Sudafed.
JWT's haul is also expected to include HSBC Republic, the private banking operation, Hoover, Thames Water, the scooter manufacturer Piaggio, and Duchy Originals.
Staff from Bates UK will join JWT to service the accounts, raising hopes that more than half the 120 jobs at the London office can be saved.
Meanwhile, 141, the Bates integrated marketing specialist, will be retained, but under the wing of WPP's Ogilvy & Mather. O&M's British American Tobacco business will complement the BAT brands handled by 141.