Feathers have their own rigidity and make up the wing blade.
Bird wing bones have only to support the feathers. Bat wings, where the elongated digits support the wing, and pterosaur wings, where the elongated 4th digit supports the wing, have rather different structural plans from one another, and from bird wings. The 3 wings on the self test certainly fail the test of structural similarity for evolutionary homology. The failure supports the hypothesis that they evolved independently, and hence are analogous or homoplastic characters, not homologous characters. However, homology is a deep concept and you need to take care with it.