Alicia, what do you mean by bad weather? Most people are under the impression that the only days to shoot are sunny days. Professionial photographers pray for overcast days. The cloud cover acts as a filter and gives skin tones beautiful luminosity and form. On sunny days shoot in very early morning or late afternoon with the sun behind the subjects. Overhead lighting like this is very harsh and is causing a lot of squinting.
The photo is more about the landscape than the family, some cropping is needed. The faces are blurry, are they clearer in your reference?
Look up Frank W.Benson's immpressionist work at
http://www.frankwbenson.com/. He did great stuff with multiple figures.
Your size seems a bit small for this undertaking. Also, don't believe the father one bit when he says he doesn't care about resemlence, HAH! Wait 'til the first relative scrutinizes it. They aren't always kind to the artist!
It is very difficult, I know to do a four figure photo session let alone the picture. I would go to a photo store, check out some books that include tips on group shots and reshoot.
If you are just starting out you want to give yourself all the help you need. You have to be firm with your clients. Remind them that in the past they would have had to spend more than one more Sunday morning doing this. It is very important for you to set high standards for yourself and your clients from the beginning.