Further , although Zhu Youwen was not a biological son , he was the oldest among his surviving sons ( as his only older biological son , Zhu Youyu , had died earlier ) .
Oldest was seriously contemplating passing the throne to Zhu Youwen .
Further , although Zhu Youwen was not a biological son , he was the oldest among his surviving sons ( as his only older biological son , Zhu Youyu , had died earlier ) , and he was seriously contemplating passing the throne to Zhu Youwen .