In 1976, the FBI assembled a report on the Weather Underground that included Sheila and George on the same list as Bill Ayers and Benardine Dohrn.
This is inaccurate. Sheila and George were never members of the Weathermen or the Weather Underground.
However, because they had known and worked with a number of the SDSers who chose to go underground as the Weather Underground, and because of their ongoing activism, they were included in FBI write-ups of possible Weather Underground associates.
Sheila disagreed with the “small vanguardist strategy” adopted by the Weathermen, which she saw as undermining the efforts to build mass movements in the United States that could bring about real political change.
Eventually released under the Freedom of Information Act, the document is available through the FBI’s web site.
Here’s the FBI’s profile on Sheila as part of the Weather Underground network: