While not definitive, here's a little history on the name Moonyean [link].
Quote:
[Smilin' Through] was made 3 times the most successful being the 1932 version. Details below. You will note that Moonyeen Clare was not actually a starlet, but was one of the characters in the dual role played by Norma shearer.

Later, in the same posting is a purported etymology. You might want to look up a copy of the play or a biography of one of the playwrights. (And, welcome aboard.)

Ceci n'est pas un seing.