I got flagMOTION which is a low polygon modeller and animation creation toll like MilkShape 3D. This tool is used to create MOD as well as MilkShape.
But, it seems that flagMOTION has an interesting feature. This tool can load BVH from Poser or BioVision. Therefore, I may be able to use flagMOTION as an animation merge tool. I'll try it.
In addition, flagMOTION can export data as OGRE XML model data. It sounds interesting.