Not quite accurate--Ananda was Prince Siddhartha's younger step sibling.

Their mothers were sisters. So Ananda was Prince Siddhartha's much younger step sibling. His own mother died after childbirth. The King Sudawdanna had 4 main wives, they were not serial wives--but parallel wives. Note--Gotami's only husband was the king. AI Overview

https://upload.wikimedia.org/wikipedia/commons/3/39/Yasodhara.jpg

No, Ananda was not Yasodhara's brother; Ananda was the Buddha's cousin, while Yasodhara was the Buddha's wife and also his first cousin. Yasodhara's father was the brother of Queen Maya and Mahapajapati Gotami, while Ananda was the son of Mahapajapati Gotami, making them cousins through different royal lineages. Yasodhara's Relationship to the Buddha and Ananda

Wife and First Cousin: Yasodhara was Prince Siddhartha's (the Buddha) wife and his first cousin.

Family Connection: Her father was the brother of the Buddha's mother, Queen Maya, and his aunt, Mahapajapati Gotami.

Ananda's Relationship to the Buddha

Cousin: Ananda was a cousin of the Buddha.

Son of a Royal Family Member: He was the son of Mahapajapati Gotami, who was a sister of the Buddha's mother.

Therefore, while both were related to the Buddha, Ananda was the Buddha's cousin and Yasodhara was the Buddha's wife, and also his first cousin. They were not siblings.