The Merge Window allows you to merge a model file into the current model. After selecting a model file you will be prompted with the merge window to specify the location of the new model in the existing model as well as options for importing textures and animations.
The merge location frame is made up of two components, the Rotation and Translation components.
The Rotation specifies how the new model will be rotated relative to the existing model. You can rotate the new model on all three axes. Rotation is specified in degrees. The Translation specifies the location of the new model relative to the origin of the existing model. The translation is specified in GL units. The relative position will depend on the scale of your model. As a guide, the small number in the lower-left corner of the viewports tell you what the GL unit distance is between each grid line in the viewport.The Include textures checkbox allows you to specify if textures from the new model should be merged into the existing model.
The Include animations checkbox allows you to specify if animations from the new model should be merged into the existing model. If this checkbox is selected, you can also specify Animation Options
The Append animations checkbox will make the animations of the existing model and animations of the new model separate animations. Both models will appear in each others animations, but only one will animate. This only applies to the merge. After the models are merged you may modify the existing animations to animate both models.
The Merge if possible checkbox will attempt to combine the existing animations of both models so that both models are animated in each animation. In order to merge animations you must have the same number of animations in each model and the frame counts of the corresponding animations must also match (if model A has animations with 10, 15, and 12 frames, and model B has animations with 10, 15, and 12 frames they can be merged). Skeletal and Frame animations are merged independently. If you have a model which contains both types of animations and one type can be merged and the other cannot, the mergeable type will be merged.
Note that you can merge skeletal animations using the Animation Sets window even after the model has been merged. Frame animations cannot be merged through the Animations Sets window.
Press Ok to merge the new model into the current model or press Cancel to abort the merge.