Valentina Baciu’s genealogical notes continue with this snippet:
Jean de Montfort, Simon’s nephew, was revered as a saint after he died in 1249 in Cyprus. I have just found that. As a strange coincidence, his wife (mother of his only daughter and heir of Montfort l’Amaury, the famous Beatrice de Montfort) married later Jean de Brienne and had Blanche de Brienne, Baroness Tingry (c. 1252- c.1302). In September 1285, her daughter Margaret de Fiennes, married Edmund Mortimer of Wigmore, 2nd Baron Mortimer, the son of Roger Mortimer, 1st Baron Wigmore and Maud de Braose.