Iwatsuke family

...At this time, branch families such as Okazaki (Mitsushige), Anjo (Chikatada), Noumi (Mitsuchika), Nagasawa (Chikanori), Katahara (Yosoe), Takeya (Moriie), and Goi (Tadakage) were established, but there is no evidence that the branch families in the western part of Hoi County below Katahara were Nobumitsu's children. Nobumitsu is thought to have been succeeded by his eldest son, Chikanaga (Iwazu family), but the Iwazu Matsudaira clan was wiped out in a battle with the Imagawa clan in 1506-08 (Eisho 3-5), and its descendants and lineage are unknown.
[The road to becoming a Sengoku daimyo]
The family that succeeded the Iwazu family as head of the Matsudaira clan was the Anjo family, whose founder was Nobumitsu's third son, Chikatada.

*Some of the terminology that refers to the "Iwatsu family" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…このころ岡崎(光重)，安城(親忠)，能見（のうみ）(光親)，長沢(親則)，形原（かたのはら）(与副)，竹谷（たけのや）(守家)，五井（ごい）(忠景)らの庶家が成立したが，形原以下の宝飯（ほい）郡西部に分立した庶家が信光の子であった確証は見られない。信光のあとは長子親長(岩津家)がついだとみられるが，岩津松平一族は1506‐08年(永正3‐5)の今川氏との戦闘で滅び，後裔や系譜は不明である。
［戦国大名への道］
　岩津家に代わって松平氏の惣領となるのは，信光三男という親忠を初代とする安城家である。…

※「岩津家」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報