The actual solution is at the top selected answer: Combine/Consolidate to one and then you can make one ABP and use it for all of them.
For instance, if you are using the Mixamo Pack, you assign all joints in all characters to be controlled by a common humanoid/biped “.” *This “” is simply a list that assigns how each bone is going to be controlled by the AnimBlueprint so that, for instance, if a joint is called “lower arm” in one and “forearm” in another, they both get the same information from the AnimBlueprint regardless of their original names.
Once you have all bones conforming to one (ie. a list of bones with a common naming convention), you can then retarget all animations to this common and apply these animations to different characters regardless of their size.
Since this is too long a process to describe in detail here, please review these two document pages on the subject:
[Animation Retargeting (Same )][1]
[Animation Retargeting (Different Skeletons)][2]
ALSO: Opening the Content Examples: Animation Map in UE4.11 or later should prove useful in understanding how one can be used for multiple/different sized characters:
*Understanding this concept is key to understanding this entire workflow solution.