When you are finished working with animation on multiple layers and you want to keep the final result in a single layer, you can merge selected layers into a single layer. You can also merge layers to filter the animation onto different layers.
Use the Merge dialog settings to specify how you want the merge to occur. See Merge dialog box.
See Merging FBX data into the current scene for information on what happens to animation layers when you merge scenes.
To merge layers:
You can also right-click on one of the selected layers and select Merge from the context menu.
Merge dialog box
Depending on what you selected in the Merge dialog box, the animation from the selected layers are either merged onto a new layer or to the BaseAnimation layer. All of the merged properties display with keyframes on the BaseAnimation layer.