My point for starting this conversation is find a solution to create pattern piece, which has parts of other pattern pieces. The example is raglan sleeve.
The first method is to create front and back panel of the shirt with raglan sleeve markings. When creating the sleeve, try to draw the same lines and curves to the sleeve shoulder.
The second way is to create the normal shirt with sleeve. Then marking the raglan sleeve on back and front panels and copying those parts and attaching those to the sleeve. Similar to the way of working with paper patterns. Currently this method is not possible, because the copied part can not be attached to another pattern.
This first way is clear and straight forward. The raglan seam is limited to to the recreation to the sleeve head.
The second way can be added to any already made pattern. There is no limitation to shape of the raglan sleeve. Here is an example of the seam
As i mentioned the raglan sleeve is just on example of this kind of pattern manipulation. The are many more cases for this kind of cut-and-paste type of operation.
The problem is here, but what is the solution.