How to change restpose of armature while still preserving animation data? I purchased BVH files containing Horse locomotion data. I want to retarget them to my custom Rigify Horse Rig. 

the only thing thats stopping me is that the armature from BVH has restpose with all bones laying flat on the ground. instead of usual T pose. so the rotation translations for them are driven via this pose. is there way to convert animations for this restpose to that from a T pose?

I also got a seperate Tpose BVH file for the same armature above.. but that also has a restpose with bones laying flat on the ground. 

Is there a way to use Tpose as restpose and convert/translate teh animations based on this pose?
was able to achieve the required result with Blender MoCap tools. I used the T-Pose BVH file and applied rotation scale and location to the TPOSE and set it as restpose.. then i imported gallop BVH file and using mocap tools i mapped the rotations to the first armature.. I was then able to retarget to my Custom RIgify rig with usual workflow.