I don't show Edmund and Mohun had any children at all. I have just done an extensive study on the matter, as he was engaged in being Lord, with his nephew Edmund, son of John being his heir apparent. This Edmund died c 1313-1314 and he had been married to Joane fitzWilliam, daughter of sir William Deincourt. JOan and Edmund, the nephew had a daugher Isabel who was a minor 1317, living 1325 but died before 1327, when Edmund the Uncle died
There was an application of Edmund, the uncle husband of Mohun to Parliament, then by Letters Patent because he was dsp himself, his Lordship would transfer to Isabel, the grand niece, and he sought dispensation to have his titles and land that went with it to go to John Deincourt of Parkhull, a distant cousin of the Roger Deincourt line. This was accepted. In 1325, Edmund the Uncle transferred Plumtre als Plumtree Manor over to William FitzWilliam, and the heirs of him, including John, Thomas of Mablethorpe, Joan and Isabel. In 1327 Edmund the Uncle's Inquisition, his heirs were Master Oliver Deincourt, who could be a brother, I did not look into it, as if he was he was also dsp, John Deincourt of Parkhull, et all. There was no William the son nor William the grandson.
For this to be so, the Grandson would have had to die dsp before him, and before 1314 when he made the initial application to parliament. If I had an email I would send you my file on this. Cheers.
ego...@telus.net