After drawing a parting line with the splitline tool, I can only get the draft tool to draft perpendicular to each segment of the parting line, resulting in 3 different faces. What I want is one single face with the same angle so that the draft coming from each segment is parallel as shown in my pictures. Any help appreciated, thanks! 

Here is what I'm getting:

Result with 3 different faces:

What I want to achieve: 

Also, when I use the neutral plane draft mode instead, it will just create the draft from the neutral plane and ignore my parting lines.