Denton Hall and Wilde Sapte have been instructed to handle the collapse of TransTec.
It is the first major joint project for the firms since they announced their merger.
The Midland-based engineering group TransTec was founded by disgraced former paymaster Geoffrey Robinson. He left the group in May 1997.
TransTec called in Arthur Andersen as administrators over the new year after the discovery of accounting irregularities amounting to £12m.
Calls have been made for an investigation by the Serious Fraud Squad after allegations the liability had been hidden from shareholders.
Wilde Sapte insolvency partner Mark Andrews, who is leading the team of Wilde Sapte and Denton Hall lawyers, says: “It is the biggest receivership for some years.”