Fan Casting "Miua" in TMNT: Enter The Shredder

Splinter tells his sons a story about how he and Shredder were actually (adopted) brothers in 60's Japan, and both fell in love with the same woman. Years passed, and Splinter married the said woman, giving birth to Miua and giving jealousy to Shredder, who killed Splinter's wife accidently while trying to kill him. He also stole Miua and adopted her himself, with Miua revealed to be non other than Karai.