Load a model into 3DXchange.
Double click on any one of the channels for the model.
In the explorer, check the box and select an image. Click the Open button to load the image as one of the textures.
3DXchange skips 'including the image file' when you export the model. Instead it records the path of the external file to keep the file size smaller.
If you modify the image file by means of any image editor, the textures for all the objects that share it update altogether.
In 3DXchange, you may also define different meshes to use the same textures and material settings by using the Pick and Paint tools in the Material section.
Select one mesh from where you want to share the textures and material settings.
Press the Pick button and click on the face of the material for sharing. The texture images and the material settings are thus retrieved.
Press the Paint button and start to click on the target faces.
Repeat step 3 until all the target faces are assigned with the same textures and material settings (press ESC to cancel the Paint mode).