How could I resist this! Such a gorgeous composition. In fact I think it's about perfect. A composition should guide the eye around the painting. Starting at one point and coming full circle. There are many ways to do this. One is the actual position of the subject matter. Other ways are with color and lighting. The linear aspect of this painting is so fluid. It's almost a heart shape the way they're sitting. The arms and hands are perfectly placed as if I moved them into position but I didn't. It's really going to be great with dramatic lighting.
The old artist me would have taken a picture and had it made into a slide. Then projected it so I could trace the lines. I know that sounds like cheating but it's really not. It saves so much time and you end up redrawing the whole thing anyway. But I just would rather sketch it on and hope for the best. I did that once before with figures and I think it turned out well. It may not look 100% like the person but it's a more painterly way of doing things.
Now the background will have to be much more interesting than in the photo. They're actually sitting in a little stroller at the zoo but it's bland. I'm going to think of something much better but not sure what yet.