Hi. A bit of clarification:
1). S4S uses cut numbers to define what part of the mesh in the original package will be replaced with what part of the mesh in the imported blend. The order is very important. Remember that you are not creating a package from scratch, you are replacing the existing information. Unfortunately, not all of it is easily edited, which leads us to the next step;
2). So there is this thing called slotrayinteractions which basically dictates the position of arms in the game. The parts of the body that contain, like, groin/thigh area have that information while a necklace or a ring do not. So when you clone a ring and import a whole coat in it, you introduce a lot of new bones that are not listed in slotrayinteractions. And this can cause extreme distortions. If you won’t see it in your game, someone else might see them in theirs. So instead of cloning a accessory, it would be a better idea to clone something that already comes with those bones like, for example, a lingerie set or something similar that is made of one meshgroup. If you will delete the body parts, you will have no problem converting it to accessory;
3). When choosing the reference for weight and uv transfer, you should be picking not something that is of the same category of clothing, but something that is of the same length, has the same bottom (skirt or pants/nude legs), has as little sculpted details as possible. So if you’re making a coat that does not reach knees for feminine frame, you can clone DressPanels. Bear in mind that this item comes with skirt bones so you cannot import in in the lingerie set. It is best to just delete those bones
Thanks for the cut numbers explanation. I was thinking that you'd use an item of clothing to transfer weights and the UV_1 from because, like you said, a ring would not have the appropriate bones or an appropriate UV_1 map.
So, you wouldn't use a ring or bracelet for the final package? I wanted to be sure I was giving the right advice, so I took a look at the CAS part of the accessory jackets I have for Sims 4 and it looked like many of them used a ring or bracelet for the final product. As in, a ring or bracelet was cloned for the final package file. So now I'm a bit confused.
Dang! Every time I feel confident that I know something I find out I'm wrong.