If she is using Live Mesh with a different LiveID, then you can simply sign into her Live Desktop at
www.mesh.com to use the remote access feature.
Alternatively, you could sign into the Live Mesh client on her PC with your Live ID, which should make it available to your Mesh, I believe.
A machine typically belongs to a single Mesh. You can share folders between meshes by using the invite feature, but there is no facility to share remote desktop access.
-steve
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