Complex sentence: The co-op was founded in 1958 or 1959, and as of 2010 continues to operate, with twenty families (down from its heyday of 250 families), some of which are second generation members of the co-op, and it is open to new members.
Split into simpler sentences: The co-op was founded in the late 50s, and as of 2010 continues to operate. Some of which are second generation members of the co- op. It is open to new members.