Since Trekkiegrrl's M4 younger package is now available again, there's my instructions to make "David" for M4:

Inject Trekkiegrrl's M4 Younger and Morph++.

Full Body Dials:

Smooth: .32

Thin: .11

Young: 1.0

Trekkiegrrl's morphs:

Set Soften Face, Jaw Corner's in, Chin Clift Remove, Nose Younger, Chin Smaller, Cheeks softer, Mouth Softer, and Chin Higher ALL to 1.0.

Scale character to 92%

Enjoy.