Okay so I am converting items for my own personal game play.The platform i use for my game requires one texture only but the items that I am converting has up to three or four different textures and come in as separate meshes. My goal is to have one item with the textures merged to fit into the merged mesh. I already know how to join the meshes I just need to know how to get the textures to align with the mesh.
Add a new UV set in the Properties panel , and unwrap the mesh in Edit mode using that UV set. Open a new image texture in the UV Image Editor at the size you want the final to be, and in the Render tab of the Proiperties panel, open up the Bake tab. Select 'Textures' and then press 'Bake', and you should see your existing textures from the object appear in the new image. Save it, and then set it in the material's texture stack for actual use.