These should link to the bvh armature’s pose as the target. So, under your model’s armature pose node, go through every major bone, and add Copy Rotation and Copy Location constraints. I know it’s not the most elegant solution, and if you know of a better way, by all means let me know. The final process is to use the constrain bone tool to link the two armatures together. Now you have your model with it’s own armature (in a t-pose), and a standalone armature imported as bvh with the pose or animation you want to use. Either delete or fix these bones (I would just delete them).