Alan burst onto the scene performing alongside his brothers Wayne, Merrill and Jay on “The Andy Williams Show.”

Alan burst onto the scene performing alongside his brothers Wayne, Merrill and Jay on “The Andy Williams Show.” He formed a barbershop quartet when he was just 12 years old.

He helped write some of the Osmonds’ hits “One Bad Apple” and “Crazy Horses.”

“Crazy Horses” peaked at number 14 on the US Billboard Hot 100 charts, reached number two in the UK, and was a major hit in Ireland, the Netherlands and Canada.

Alan met his wife Suzanne Pinegar, a cheerleader, at a Brigham Youth University basketball game and they had their first date at Y Mountain in Utah, the Herald Extra reported.

They tied the knot on July 16, 1974, at the Provo LDS Temple – but Alan was back on stage that night, performing two gigs in Las Vegas.

Alan said that Suzanne “stole his heart,” while she admitted “When I said yes, I’ll marry you, I didn’t know what I was getting into.”

Despite his MS diagnosis, he refused to be defined by the condition and lived by the motto, “I may have MS, but MS does not have me!”

But, his illness forced him to ultimately retire from live performing.

“I was on stage and couldn’t raise my right hand,” Alan previously said.

“I trusted my heavenly father. You have to have opposition in life — this was my test.”

Merrill Osmond revealed his brother was “struggling” two days before his death.

“I was blessed to sit quietly with him,” he wrote on Facebook.

“We talked as brothers do, heart to heart. He was struggling, but when I shared a joke or two, he found the strength to chuckle… and then he smiled.

“My brother has now stepped into the presence of our Father in Heaven with honor and peace. His life was not measured in years, but in love, sacrifice, and purpose.”

Merrill described Alan as a “missionary” and a “saint” before telling mourners “don’t let your hearts be heavy.”

“Don’t weep for him. Rejoice, knowing that your brother, your friend, your hero is no longer in pain. He is free. He is whole. He is home.”

Alan is survived by his wife, Suzanne, and their children.

His son David, who appeared on the eighth season of “American Idol,” was diagnosed with MS in 2005.