If you are on the board of an LPFM station you can not be either on the board of another LPFM station nor can you have an attributable interest in a full power AM, FM or TV station. There may be exceptions if the LPFM station is licensed to a university that also has a full-power station and the LPFM is operated by the students and shares the same board of trustees.
You may have an ownership state in up to two FM translators if the translators are commonly-owned by the LPFM station's organization, carries the LPFM station's primary audio (the HD1 stream if the LPFM station is digital), has a service contour that overlaps the LPFM station and is located within 20 miles of the LPFM station (10 miles in Neilsen Audio markets 1 through 50).
To put it simply in most cases, if your name is on an ownership report (for a full-power station), it also can't be on the board of an LPFM station.
This is not legal advice. REC recommends obtaining the services of a qualified attorney if you have any additional questions.
https://recnet.com/73860 (Cross ownership)