The already made clothing is not the problem^^
The Creation Kit for TMP looks like 6 white Boxes which you rez on the ground.
The Creator can then put uploaded textures into these Boxes and can then create clothing (or tattoos) with these Boxes.
And that is the problem, she can "feed" these Boxes with textures, but then she can't use them, if she clicks on them they show no reaction, no menu, nothing,
I don't think there was an update 3 days ago or today. I will ask her to use another viewer to see if that fixes that problem.
Well, yes, scripts work where she creates the clothing, because she has to do this in public sandboxes (Landlords don't like it if their tenants rez 500 to 600 prims, even if its only temporary).