what game engine are you using? in some engines you could apply the overlayed normal map in the shader, and use worldspace coordinates to project the detial normal on the model instead of relying on the UV's that have seams.
What woudl be the use for detail normal map in xnormal? I specifically avoided to sculpt brush out the fur in the slips couse I tought to add a more detailed / matching to photosource texture with crazybump , is not that the seam are all that noticeable and I could hide them with an extra polygon shape in alpha texture but…