You could work on framing the adults head more. Lions heads have a very boxy appearance to them due to the way that the mane grows out of the sides of their faces, pushing the mane forward and making the hair bunches bigger might help the design.
Lion mane hair forms very tight clumps, kind of like how people like to draw anime hair actually.
Here are some examples of what I am talking about with the head.
Perhaps consider smoothing out the skin area on the cubs stomach right in front of the sartorius, the bottom angle seems a bit rough in that area for a part that is normally very smooth in appearance.
That aside, I think the posing is delightful, and the musculature seems to be spot on. The bodies look solid, just work on that mane.