Merging FBX tiles in a single model file

I would like to obtain a single FBX file for a 3D photomesh, with texture. As the original scene is quite large, I use Bentley ContextCapture Master to generate tiles (a dozen), each being in FBX format with the .jpg texture on each tile. I cannot do the model in a single file (no tiling), because this would take +100Go RAM.

As I have to import this model in a software (Lumion) that recognizes .fbx + .jpg, I would like to merge all the tiles in a single FBX file.

Do you know if there is any solution for merging this tiles and textures, in a single FBX + JPG pair?