Which free mesh editor is best for combining models then what Rhino command to auto curve the mesh?

I am using Agisoft Photoscan but just discovered it can’t bring together models from two or more photo sessions (chunks) such as when you turn an object upside down to photo session its underside, its marker tools to do so are 3500 euros away from me versus 179 for the standard prog, which needs these markers to do the standard job of combining models !

plan B get the models into a free mesh editor and align by three or more points in that.

When combined I then need to bring mesh into Rhino, and create original surfaces using our normal tools.
Is there a command that will make a good initial stab at placing curves and surfaces onto a mesh of an item, especially if it was originally an engineered metal object ?

Else could I bring the meshes into rhino and view them with their textures applied from the jpg’s, (i.e. looking as they do in the final stage of Agisoft), use orient3pt then curvetool and surface them up ?