Fifteen former senior managers of Hillier Architects, a practice that sold itself to Scotland-based RMJM in a deal completed in 2007, have filed a lawsuit in New Jersey state court to force RMJM to pay bonuses that were promised as part of the sale agreement.

In completing the $24-million buyout of Princeton-based Hillier, RMJM agreed to pay-to-stay bonuses, in cash and stock, for senior Hillier managers. But as the economy worsened in 2009, RMJM CEO Sir Fraser Morrison, citing delays in projects, informed the senior Hillier managers that it would be unable to pay the bonuses on schedule and instead offered to pay them with 4% annual interest at a later day. When RMJM failed to pay the portion owed to the managers from 2009, the former employees rejected another offer of deferred payment. All the managers have since left the company.

In the amended complaint of a lawsuit filed last month, the former managers claim RMJM began shutting down operations in Philadelphia and most or all of its operations in Princeton and transferred assets from those offices to the parent company.

According to the lawsuit, filed in Superior Court in Newark, N.J., RMJM Inc. had $6 million in cash in 2009 when it owed the plaintiffs $5.5 million in bonus payments. “My clients would like nothing better than to receive prompt payment of this long overdue obligation and have this resolved as quickly as possible,” says Wayne C. Stansfield, an attorney.

A spokesman for RMJM says the company has had to manage its cash carefully over the plast 18 months “like virtually every practice” and that it is “surprised and disappointed” by the lawsuit. “The allegations of asset-stripping are both outrageous and completely and utterly untrue,” and the company has injected millions into its U.S. operations during the recession.