I was the person who correct the list of the children of Frederick II with Isabella and Yolande. Sorry for not post my name. I am very confuse for the exact number and names of the children of Isabella of England. Really existed Jordanus?, how many children had Frederick in this marriage, four or five?, Margaret was the eldest or the youngest? the child who gave birth Isabella and cause her own death, died shortly after, was stillborn or live?. Thanks.