Two of her granddaughters , Sophie and Hedwig later joined it , one of them as abbess .
The nunnery at Rijnsburg was established by Petronilla in 1133 .
Two of Petronilla 's granddaughters , Sophie and Hedwig later joined it , one of them as abbess .
The nunnery at Rijnsburg was established by Petronilla in 1133 .