Which preposition to use with suffragans

in Occurrences 3%

The king insisted upon sureties; and Becket desired leave to consult his suffragans in a case of such importance [k].

of Occurrences 3%

Mont Gisart was a castle and feif in the county of Joppa, with an abbey of St. Katharine of Mont Gisart, "whose prior was one of the five suffragans of the Bishop of Lydda."

Which preposition to use with  suffragans