This particular Sir Richard Tunstall was a Knight of the Garter and married Elizabeth Franke.
They had one daughter of record, Elizabeth Tunstall, b: 1420 in Thurland Castle, Lancashire, EnglandElizabeth married Sir Robert Bellingham (both are my direct ancestors - 14th Great Grand Parents)
Sir Richard was born between 1400 and 1403 and died about 1492 according to Burke's Peerage & Baronetage, 106th Edition, Charles Mosley Editor-in-Chief, 1999, Page: 244His parents were Sir Thomas Tunstall and Eleanor FitsHugh.Sir Richard Tunstall and Elizabeth Franke were my 15th Great Grand parents through one ancestrial line.
Sir Richard was the brother of your Sir Thomas Tunstall who was the grand father of your direct ancestor Marmaduke.i.e. Marmaduke - son of Brian "The Stainless" who was the son of Sir Thomas (brother of Sir Richard).
Ironically, the brothers Sir Thomas and Sir Richard had a sister names Jane Johanna Tunstall who married her second husband Sir Sir Roger Warde/Ward. Johanna and Roger were also my 14th Great Grand Parents through a differnt ancestrial line.As such, Jane Johnanna Tunstall's and and Sir Richard Tunstall's parents (sir Thomas Tunstall and Elaeanor FitzHugh) were both my 15th and 16th Great Grand parents based on the two direct ancestrial lines.