Complex sentence: Researchers have found that OA members with excessively rigid plans are less likely to remain abstinent, they suggests that new members start with a some-what rigid plan that becomes increasingly more flexible approaching the end of a year in the program.
Split into simpler sentences: Researchers have found that OA members with excessively rigid plans are less likely to remain abstinent. The researchers (not OA) suggest that new members start with a somewhat rigid plan that becomes increasingly more flexible approaching the end of a year in the program.