B M Lanong, an MLA of the United Democratic Party (UDP), a key ally of the Congress, was sworn in as deputy chief minister. J A Lyngdoh (UDP) and independent A T Mondol were also sworn in by Governor R S Mooshahary.
Sangma's government would be the 22nd in the state in its 38 year history and the 11th in the last 10 years.
The month-long rebellion by Congress MLAs peaked on April 17 when Sangma and dissident Congress legislators rushed to New Delhi with the claim that Lapang had lost majority.
The development came a day after 20 Congress MLAs in the 60-member House met at Sangma's residence and pledged "unconditional support" to him.
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