Who are the people mentioned in the Sint-Jan charters #501 and #504?

Look here for the documents.

In 1538 Meth van Osenbrugge goes to Boerman Gaertszoon and Herman van Essen to complain about Arnt (probably Van Eyll) trying to buy the house, named "The Parrot". She claims that the house was promised to her by her cousin Andries Andrieszoon, a priest. These 2 guys then go to the aldermen (Wynant van Doernynck and Johan van Mekeren) in Arnhem to register the complaint.

Then 2 years later, in 1540, the children (Meth and her siblings) of the late Gerartz van Osenbrugh: Arnt, Jansz, Jacob, Aleydt and Met actually officially sell the house to Arnt van Eyll. Since they are under-aged they are represented by Engell Zerriszoon Sailmaker and his wife Jenneken. The procedings take place in Nijmegen with Lambert Valckenborch as judge and Conrad van Doirnick and Pontiaen Groenwalt aldermen.

So, who are these people?

"Defendant":

Arnt van Eyll. The van Eyll family were nobles in the Gelre area, Cleves, Arnhem and Zutphen. Arnt's father Willem van Eijll (married to Christine van den Sande) was an alderman in Arnhem in 1540 and later became burgomaster there.

"Plaintiffs":

Who are the children of Gerartz van Osenbrugh and his nephew Andries Andrieszoon?

According to the document, Andries Andrieszoon was a priest and a cousin of the children of Gerartz van Osenbrugh.
A strong argument can be made that he is the same person as Andries Andrieszoon Yseren, who was a Kanunnik, and a nephew to Gheryt van Ossenbroeck.
Andries Andrieszoon Yseren's cousin Arend Yseren (an alderman in Zutphen) was also involved in the St. Jans Commandery in Arnhem. See his seal below.

Another cousin, who was closely involved with the Commandery of St. Jan in Arnhen was Gerrit Schimmelpenninck, the son of Jutta Yseren. He lent money to them. Read the information here.

Commanderij van Sint-Jan te Arnhem
Inventaris
1. De commanderij van St. Jan te Arnhem
1.1. Stukken betreffende de commanderij in het algemeen
1.1.7. Geschillen
50 Briefwisseling tusschen den commandeur van St. Jan te Arnhem en de weduwe van Geret Schimmelpenninck over een som gelds, welke deze aan de commanderij geleend zou hebben, 1526, 1527. 5 stukken in een omslag
N.B. Met een afschrift van de bedoelde schuldbekentenis, 1490.
Reg.nos. 428, 490, 491, 492 en 493.
Vindplaats: Gelders Archief



View a family relationship chart here, also assumimg that Gerartz van Osenbrugh is the same as Gheryt van Ossenbroeck.
This is not a clickable chart. You can get a similar clickable chart from here by clicking on a name and then the "Family" tab.

"Commissioners":

Engell Zerriszoon Sailmaker. The Sailmaker family also often used the van Rechen name interchangeably. They were goldsmiths (in Arnhem and Emmerich) and some (a.o. Johan and Hendrick) were in charge (commander) of both the Sint Jan's Commanderies in Arnhem and Nijmegen. They must have been close to Gerartz van Osenbrugh to act as his children's commissioners.

"Witness":

Herman van Essen was feedmaster of the Court (lees hier) in Arnhem from 1538-1542. He was also a member of the (prestigious) St. Erasmus Fraternity in the St. Walburg church in Arnhem.
The van Essen family were nobles and part of the "Ridderschap van de Veluwe", going back to the 1200s.

Rekening van de voedermeester Hermen van Essen van ontvangen en te Arnhem weer uitgegeven haver, 1538-1542.
N.B. De voedermeester ontving graan van o.a. de korenmeester van de Veluwe. De uitgaven zijn dagelijkse lijsten van de tot de hofhouding behorende personen wier paarden gevoederd zijn, met per persoon het aantal paarden. Daaraan toegevoegd nog enkele aantekeningen van uitgegeven haver. Op beide rekeningen aangetekend "Pro domino".

"Judge and aldermen":

Lambert Valkenborch was a judge in Nijmegen in 1540. In 1547 he was captured in France and held for a ransom. In 1559 there are complaints in the city council that he has a French mistress: "..blijkens een raadsignaat van dat jaar, klaagt over dat Fransche concubin van Hr. Lambert Valckenborch". Oh là là.

Wynant van Doernynk was an alderman (schepen) in the town of Arnhem in 1538. He was also a member of the (prestigious) St. Erasmus Fraternity in the St. Walburg church in Arnhem. He died in 1544.

Conrad van Doirnick (his brother?) was an alderman (schepen) in Nijmegen in 1540 and also involved in the Commandery of St Jan in Arnhem.

Johan van Mekeren was an alderman in Arnhem in 1538. The Mekerens were nobles and had high positions in Arnhem and De Veluwe area as judges, burgomasters and aldermen. Johan was also a member of the (prestigious) St. Erasmus Fraternity in the St. Walburg church in Arnhem and business partner with Wynant van Doornik above.

Pontiaen Groenwalt was alderman in Nijmegen in 1540. In 1528 he was "dingmeester" for Karel van Egmond.
Read an interesting tale about that here.

His ancestor Arndt Groenewoud (-walt) was a commander of the St. Jan's Commandery in Arnhem.

Ref: https://www.veluwsegeslachten.nl/openbaar/more/jon_arnhemse_broederschappen.pdf