I'd like a number of my dogs together in one portrait, but I don't have a good photo of them all together. Is this possible?
It's perfectly possible to commission a group portrait! It's actually very rare that I use just one photo for a group portrait. Usually I assemble a large commission like this from several separate photos. To give you an idea, here's an example of a pastel commission for four small dogs together on 24" by 18" paper.
Here's another commission completed by piecing together separate photos of two beautiful West Highland Terriers, and placing them into a beach scene (again using different photos for each dog):