一弟 or 三妹?

一弟 or 三妹? I'm going to be promoted again. I'm 一姐, Shaine is 二姐 and baby is 一弟 or 三妹. Haha... The same question was posed to me again? Is baby boy boy or gal gal? I told Ah Ma, baby is 一弟. Mummy said it could be 三妹 too. If it's 三妹, I got to think of a new name for her. She will be Zi-XX... No more Zi-Zhu(spider) as Shaine pet name is called Zhu Zhu.