I thought Dharma was initiated by the Hanso family. The Hansos connection to the island was a crewmember of the Black Rock who crash-landed on the island back when it was off the coast of Madagascar. I was figuring that at some point in the 1970s, the Hansos figured out where the island was again and hence started the Dharma Initiative.
I don't know if this helps but I got it all from Lostpedia:
The Hanso Foundation is an organization founded by Alvar Hanso, aiming to "reach out to a better tomorrow" by researching ways to preserve human life and promote well-being. It was established approximately around the 1960s, with Alvar oddly moving from a successful background in munitions selling and weapons armament to becoming a philanthropic entrepreneur. Among other projects, the Foundation also financed the DHARMA Initiative.
According to various orientation films, the Initiative was founded in 1970 by Gerald and Karen DeGroot, two doctoral candidates at the University of Michigan. It was or still is financially backed by Danish industrialist and munitions magnate Alvar Hanso and his Hanso Foundation.
Alvar Hanso, great grandson of Magnus, appeared in the 1975 DHARMA Orientation Film, introducing the DHARMA Initiative to recruits, and explaining its purpose to the world. The project began due to Alvar discovering the Valenzetti Equation, which had been commissioned by the United Nations in 1962. Its findings predicted the exact amount of time until mankind extinguished itself as a species. Hanso built research facilities on "an island" to research and attempt to modify the equation's results (thereby changing the date of the "end of the world").
Not much else is said about Magnus other than he did own the Black Rock and he is apparently buried on the island.
Widmore bought that painting of the Black Rock and the Hanso diary, right? But has there been any proof that Widmore is a relation to the Hansos? Now that we see that he is an "original" Other, he can't be a Hanso, can he?
I don't think they've given us enough to speculate on any of that.