 His second marriage was with Ursula ("Frankengrüner") Grüner († ca.1484), from whom the Frisian and later the Prussian line originates.The children of Michael's and Ursula's alliance were never recognized by their half-siblings, as their first born son was born out of wedlock and the legitimisation only took place with the subsequent wedding.Johann Onuphrius (*1513–†1584), a great-grandson of Michael II.