Hi Gloria, you are indeed right. The mother must be Gijsbertje Rijswijk. See the sources in the research note.
Solution, adopt the wrong mother, change the Last Name at Birth and the first name. Place the sources from Research under Sources or cite them in the text in Gerritje Brink's profile. Enter the data from the 3 sources (Birth, Marriage and Death) in the appropriate fields. finally remove the Unsourced banner and orphan the profile again if you wish.
Gr. Joop