Complex sentence: The documentary was made independent of the estate of Pancho Barnes, however the estate cooperated by allowing the film makers full access to her personal papers and photographs as well as her copyrighted autobiography that are owned by the estate.
Split into simpler sentences: The documentary was made independent of the estate of Pancho Barnes. However, the estate gave the film makers full access to her personal papers and photographs as well as her copyrighted autobiography that are owned by the estate.