haha look at the size of her husband duke. hed pound you in the ground like a jackhammer. (just kidding. i know it was all in good fun, as was my comment)nice photo. but hard for a drawing, i would reduce the gamma, take it to sepia. the lighting is difficult. your daughter's face is very hot (in the photo sense, not the pedophile sense) and that might give you issues.
anyway, its a lovely photo of lovely family, but in my opinion you're gonna make it pretty hard on yourself to use it as a reference. but the miracle of modern technology might allow you to even out the contrast a little.
good luck and happy holidays
jai guru deva om