Align and merge two side of butterfly scan

From SLS-3 scanner I got two faces of a butterfly, I need later to enlarge, cut, 3d print and paint it.

Problem is being almost 2D I can't find enough overlapping points to perform automathic alignment and merge.

The marker I used for initial alignment (the thong holding the pin that fix the butterfly) was only on one side of the object so I can't use it for both.

So interested to know if there is any smart way to align the two side and next merge them in one single mesh, using DAVID 4 or other programs (Meshmixer, 3d-coat or similar).

Hi,
I have worked on similar assignments. So far I have stitched meshes together with Materialise Magics which has some advanced mesh editing capabilities.
I have spent many hours closing up holes manually so it would be great to find an automated way to do this.
I sometimes use Sculptris which has a reduce brush so you can reduce poly count in specific areas, making the stitching together of meshes more efficient.
Though the import - export routine in Sculptris can reduce detail in the overall mesh.

I've cranked out I think : I did use the DAVID software to manually align the two part and next fuse it together.
Using GOM Inspect for cleaning and hole closing, really fast and high quality.
Will post a couple of images next week.