She is the ONLY CHILD of Jaehaery’s ELDEST SON. It appears to be correct. The only discrepancy I can find is that there's a few characters that are missing like Aegon and Daenerys (children of Jaehaerys and Alysanne), Baelon (son of Viserys and Aemma Arryn) and some of Aerys II's children.
Ronnel Arryn, the King Who Flew, married a Stark and was thrown out of the Moon Door together with his children. His brother Jonos and any children he had were in turn displaced by a cousin. This cousin, Hubert Arryn, married a Royce (proud First Man family) and had six children. One of these children was likely Rodrik Arryn - Rodrik being Spoilers ahead. Note, this is based on George R.R. Martin's book series, but could differ from the show. If you don't want anything spoiled about House of the Dragon or Game of Thrones, stop(SPOILERS EXTENDED) House Arryn Family Tree from Before the Conquest to the War of the Five Kings, detailing the Kings of Mountain and Vale, the Lords of the Eyrie and their respective claimants r/asoiaf •