Silly goose, YHWH isn't under heaven. YHWH is the name that is above all other names. The Holy and Proper name of God given to Moses at the burning bush. Jesus, in Hebrew Yahshua/Joshua, in Greek Ἰησοῦ, is the name under heaven given to the Son, YHWH, who saves people. Thus Jesus is the name under heaven given among men, whereby we must be saved. But given that you are so, so focused on saying the right word, perhaps you should use Yahshua, the name Peter actually used on Pentecost, or maybe Ἰησοῦ the name recorded in inspired Scripture.
You still didn't answer my second question. Why is it more rational to think the Father's name is Jesus as opposed to thinking the Son has two names: Jesus and YHWH?