Mr. Arendsen,
The ordinance book, titled "Groot Gelders Placaet-Boeck" (Great Gueldrian Placard Book) as a collection of legislation texts of (collectively) the Duchy of Guelders (Hertogdom Gelre, Gelderland, https://en.wikipedia.org/wiki/Duchy_of_Guelders) and the County of Zutphen (Graafschap Zutphen, https://en.wikipedia.org/wiki/County_of_Zutphen ), seems to have appeared in 3 volumes, at least.
A register for multiple volumes together mentions this legal text, which was called [something like] 'Matrimony Regulation, or Ordinance upon the Marriages, with the annexes thereof, dated the 9th of October 1660' , as to be found in "2.D." (2de deel, tweede deel; 'second part', Volume 2). This regulation is probably what you're looking for.

Google Books has this one in its collection: https://www.google.nl/books/edition/Groot_Gelders_placaet_boeck_dl_2_bd/DmP3zsdmEHkC?hl=nl&gbpv=1&dq=Groot+Gelders+Placaet-Boeck&pg=PP3&printsec=frontcover . "Het Twede Deel van 't Groot Gelders Placaet-Boeck" (The Second Part/Volume of the Great Gueldrian Placard Book), published in 1703.
For easier reading on the computer, a PDF version is offered by Google Books here: https://www.google.nl/url?sa=t&source=web&rct=j&opi=89978449&url=https://books.google.com/books/download/Groot_Gelders_placaet_boeck_dl_2_bd.pdf%3Fid%3DDmP3zsdmEHkC%26output%3Dpdf&ved=2ahUKEwjVmfm86MKGAxUQhv0HHfVSDAgQpfACKAF6BAgGEAI&usg=AOvVaw11BhPR74Wiu3KLwNcDGIR3

The individual topics index/register, in that same Volume 2, refers to a page nr. 383 for said text:

...which is indeed where you will find that legal text, from pages 383-384:

Translating this obsolete Dutch into English, and finding the relevant section pertaining to stepmothers, will be a whole different question, I'm afraid... Lots of success!