If a bird-winged creature had shoulders inside the ribcage like a turtle, how would its wings fold up, and where on the body would they likely be held? The creature has a carapace and turtle-like back, but the ribcage has the shape of a goose's rib-cage. Its neck is like the torso of a snake. It also has forelegs, which are like an eagle's legs, and are attached to the carapage by a hip just behind the ribcage
I suspect that the wing anatomy would, like the foreleg anatomy of the turtle, extend up through the cervical girdle and would fold back over the bony carapace of the creature's back. If the carapace is small & narrow, perhaps the wings could even fold up along the creature's flanks.
In looking at pictures of turtle anatomy, I think it's not quite accurate to say the shoulders are inside the ribcage. Turtle anatomy is pretty amazing. If you look down at figure 7, I think what's going on is that the bones of the ribcage migrated outwards, and they and the scapulas did a little jig to get around each other. The musculature is otherwise normal with the shoulder bones being outside the chest wall muscles.
Not that this changes your question, but it may help clarify the anatomical imagery.