I am a Dutch descendant of Willem Dercksen Backer.
Although I have no ancestry for Willem, I can perhaps help to other ancestry of for example Geurt van Roekel & Hendrikje van Steenbeek or their son Geurt van Roekel and his wife Jantje Pothoven. Contact via www.van-steenbeek.eu
With kind regards,
Jaap van Steenbeek.