The move follows news last month that the agency's creative director, Kate Stanners, and its chief executive, David Pemsel, stormed out of the agency after a disagreement with Law, thought to centre on its future direction.
Law, the agency's chairman, and Chalk, the recently hired planning director, are now buying the agency's independence from IPG and S&J, the two silent partners.
Stanners and Pemsel are to leave the agency permanently, selling their stakes to Law and Chalk.
Boymeetsgirl has few significant pieces of business. It is on DaimlerChrysler's roster, and currently handles below-the-line communications for Total, the petrol forecourt retailer. However, the account has recently come up for statutory review (Campaign, 3 September). The agency is expected to be among a shortlist of three in the final stages of the pitch.