Thanks for the response.
Yes, I think that would give me the result I want, but it would take a lot of time to tag all of the clothing items. I have created many appearance presets with different clothing sets that I sometimes (not always) want to merge.
I think it's more convenient to first load an appearance without clothing and then merge the clothing (as I described in my previous post) rather than tag every clothing items from those presets.
I'll also try to explain why I do it this way:
When I load a scene from a creator, the female atom already has an appearance with clothing added by the scene creator. That clothing may include fluids, makeup, or other scene-specific items that are either visible immediately or will be visible later during the scene. I don't want to remove those. Because of that, when I load clothing from my appearance preset, which may include items I want to add, such as makeup, gloves, a hat, or other clothing specific to a fictional character, I want to merge it with the existing clothing.
That's basically it.

I don't want to lose any "non-real" clothing or effects that were added by the scene creator, while also being able to add clothing from my own preset. When I checked the default appearances in scenes, all of the clothing items were marked as "real." So, the easiest way I can think of to avoid losing any trully "non-real" clothing is to load the appearance preset without clothing first and then merge the clothing from the preset.
Also, I'm not asking for any new feature to be implemented. I was just wondering if there's an easier or more convenient way to achieve this using UIAssist than the method I'm currently using (manually copy apperance presets to clothing folder and use two load buttons in UIAssist)