Iarddur ap Merfyn

See Peter Bartrum, https://cadair.aber.ac.uk/dspace/bitstream/handle/2160/6516/TABLES%... (May 27, 2018; Anne Brannen, curator)

Darrell Wolcott shows that Merfyn ap Rhodri Mawr had no sons other than Triffyn:

Please see Darrell Wolcott: The Royal Family of Powys - Powys Succession after 823; http://www.ancientwalesstudies.org/id13.html. (Steven Ferry, October 15, 2019.)

Please see Darrell Wolcott: The Royal Family of Gwynedd - Wikipedia's Lame Biography of Rhodri Mawr; http://www.ancientwalesstudies.org/id165.html. (Steven Ferry, January 26, 2020.)

Please see Darrell Wolcott: The Men of Lleyn - How They Got There; http://www.ancientwalesstudies.org/id118.html. (Steven Ferry, August 17, 2020.)