Apparently in 1675, after the huge flood, Marij joined her brother Teeuwis and her parents in moving to the Dronrijp area in Friesland. Her husband Willem must have died by then. She must have married Sieuwert Douwesz there. I didn't find the marriage record, but there were a lot of Sjoerd Douwes' to go through in Friesland and no Siewerts Douwes' in West-Friesland. She is named in her mother's will dated March 25 1686 with her husband Siewert. Only her deceased brother Jan's children are listed in the will.
Sources

Baptism: Wervershoof baptism records as found at ‎[1]‎

Baptism of Marij's youngest child Jacob: 1702-03_2 DTB Andijk 2. Gereformeerde doop- en trouwinschrijvingen en lidmatenlijsten, 1667-1788 ‎(met hiaten)‎. as found at ‎[2]‎

Trijn's boedelscheiding dated March 25 1686 as found at ‎[3]‎