Could you send me a model to examine as well? I can attach .fx files effectively using C script, but whenever I try with MED either the model will not show up or the .fx will do nothing.

Some things that I am curious about, are that if the .fx file requires 2 skins do you need both skins in MED to have the .fx file attached? Or just the first/second?

If you want 2 different .fx files to be attached to the same model, and both files define their skins as the 1st and 2nd skin will you have to change the second .fx file to use the 3rd and 4th instead so that you can have 4 skins? Or will MED start counting the skin layers starting from the layer the .fx was defined?