Blend Method Visible: Instance Only, Default: Replace
In a choreography’s Action List, actions are listed in order of precedence. The default behavior for an action later in the list is to replace whatever motion was before it. However, two additional choices are available: “Add” and “Cross Blend”.
Replace: This option simply replaces the motion of one action when it overlaps a preceding action.
Add: Add makes the motion in later actions add to the existing motion, (like muscle motion). This is useful for adding hip sway to a previously designed walk cycle, or you can add some extra bounce or head bob. Add is also useful for modifying a complex or motion captured action. For instance, a tennis swing that swings a bit too low for the shot can be quickly modified with only simple additive changes in the choreography. Since this is stored as an additional rotate offset, it will be carried on to subsequent keyframes. Now the entire swing will be higher with any built-in nuances in the underlying swing motion left intact. If the arm isn't quite in the correct position at later frame, small changes can be made to the offset at that frame. The frames chosen for the offset action's keyframes don't need to match the keyframes of the original action.
Blend: Motion Cross Blend is useful for averaging between actions in the Action list. For example, a wave; can be averaged with a walk, (this technique does not make sense for choreography actions). The wave action can be created with no knowledge of the walk action.