I noticed the welds that hold hats to the head are now inside of the handle by default, when they used to be in the head. If you put a hat into the character that isn’t welded to the character, though, the automatically generated welds still go in the head. It is inconsistent.
When I try to make the weld inside of the handle before putting the accessory in the character, the character removes the weld when the hat is put in and makes its own weld inside of the head.
I’m not sure what you mean by this. The new Accessory class will create welds inside the handle, the legacy Hat class creates welds inside the head. The difference in behavior is documented on the Accessory wiki page.
It must only happen when the Attachment objects have been removed.