The two legal departments of the companies that are now Walgreens Boots Alliance Inc. spent 2 1/2 years managing the legal impact from the two-part merger.

“The fact that we were half pregnant for a couple of years was an interesting challenge form a disclosure perspective and an exchange-of-information perspective, said Jan Stern Reed, general counsel of Walgreens Boots and of the Walgreen Co. division.

In December, U.S.-based Walgreen Co. and Alliance Boots GmbH of Switzerland closed a transaction announced in June 2012. In phase one, pharmacy chain Walgreen bought about 45 percent equity stake in international health and beauty retailer and pharmaceutical wholesaler Alliance Boots for about $4 billion in cash and 83.4 million shares of its common stock.