Found a Hester Plancius in the Netherlands. But I think it might be the baptism of her child. Though you may be able to page thru the records and find her. Netherlands, Baptism Index, 1557-1902 Here is the link: https://www.wiewaswie.nl/personen-zoeken/zoeken/document/srcid/51996262
Is this the marriage of your x7 grandfather Petrus (Platevoet or ) Plancius ?
They have a daughter Johanna Esther Plaetevoet Plancius on 27 October 1676..not sure but perhaps she later was named Hester ? Do you have a bit more info, there were several Petrus Plancius and from different generations and in almost every place or archive in the Netherlands there are Petrus Plancius mentioned or to find...so a little 'hunch' or tip would really help :P