Heikki Antero Borenius, son of Heikki Borenius Sr., started working at the firm in 1947 and became a partner in 1957. The firm name was therefore changed, this time to Attorneys at law Borenius & Borenius.

The clientele of the company grew rapidly and several new lawyers were hired.

Heikki Borenius Jr. continued the fine work of his predecessors, and the firm became renowned in handling complicated cases in corporate law. The reputation of both father and son Borenius grew and the clientele of the firm included large business and industrial corporations.

In 1961, Heikki Borenius Sr. retired and Kullervo Kemppinen was offered partnership by the suggestion of Heikki Borenius Jr. Negotiations followed and it was agreed that Kullervo Kemppinen would become a partner.

In 1962, the firm name was changed into its current form, Attorneys at law Borenius & Kemppinen Ltd.

Both Heikki Borenius Jr. and Kullervo Kemppinen continued in positions of trust in the boards of directors of the Finnish Bar Association and the Association of Finnish Lawyers as well as in the Board of Arbitration of the Central Chamber of Commerce and in several committees and boards of arbitration, especially relating to patents and copyrights.

Heikki Borenius Jr. passed away in January 1988 and Sakari Sorri joined the firm to replace him.