Sewing to straighten knitted bobbing doll head

I have just almost completed knitting a topsy turvy cinderella doll. Both heads are wobbly and listing to the side. I have tried using invisible thread to “sew their heads up”, but found the thread impossible to use (too thin). Any suggestions for straightening them out would be greatly appreciated.
Thanks you inventive knitters!

Is this your pattern?

Maybe just adding more stuffing would help.