RE: Any idea how to do this??
Well you will need to install a triangle of material to fill the triangular gap that has been made at the lower surface. I would use hard balsa, carefully sanded and shape to make a good fit. Then move the hinges to the lower surfcaes. The problem is the colour match. The balsa will need to be covered with the same film covering as is currently on the wing, and I would cover this before the hingng process. If you can't get nmatching film, go for a contrasting colour.
Well worth doing on this model. good luck with it.
John