Thihathura II of Ava was the joint-king of Ava

Ava Kingdom

The Ava Kingdom was the dominant kingdom that ruled upper Burma from 1364 to 1555. Founded in 1364, the kingdom was the successor state to the petty kingdoms that had ruled central Burma since the collapse of Pagan Empire in the late 13th century...

 who co-reigned with his father Minkhaung II

Minkhaung II

Minkhaung II was the twelfth king of Ava who reigned from 1481 to 1502. His 20-year reign was the beginning of the decline of Ava's hold on Upper Burma. Yamethin, a region to the east of Ava, revolted upon Minkhaung's ascension to the Ava throne and stayed independent throughout Minkhaung's reign...

 for 15 years. He was just seven when he was appointed the heir-apparent by Minkhaung II. At 12, he was made a co-regent. He lived in the same palace with his father, and displayed a white umbrella as a symbol of sovereignty. He co-ruled with his father for 15 years but died a month earlier than his father. Minkhaung, who faced numerous rebellions throughout his reign, made his son joint-king because he wanted to retain loyalty of his son. Minkhaung outlived his son, died in March 1502 and was succeeded by his younger son Shwenankyawshin

Shwenankyawshin

Shwenankyawshin Narapati was the last sovereign king of Ava who reigned 25 tumultuous years between 1502 and 1527. A confederation of Shan states led by Mohnyin continued their relentless attacks, and gradually absorbed Avan territory from the north, while their ally Prome took Avan territory in...

(Narapati II).