I asked a similar question a while back and everyone was very helpful, but now I have more specific information and am even more baffled and frustrated than before.
I know how to do mattress stitch from garter to garter and st. to st. but now I’m trying shoulder seams and all the tutorials I can find for shoulder seams are st. st. to st. st. On one side, I have rev. st to rev. st, then 3x3 rib to rev. st., then 3x3 rib to double moss. The other side is similar, but reversed. How on earth am I supposed to do that in an even and neat way? I know shoulder seams aren’t invisible, but what I’ve come up with so far is unacceptable. 
Thanks so much.
I think most shoulder seams are done with a 3 Needle Bind-Off regardless of what stitch. It makes a nice stable seam that’s not too bulky. KH has a video for that.
Thanks, Jan! These pieces are already finished, though, would I have to unravel the bind off?
You actually bring me to another question, since you mentioned it. I’m working on another sweater now, similar construction. If I want to do the 3-needle BO instead, don’t I just follow the pattern normally, omitting the bind off row and leave those stitches on holder til back is done? That seems to be correct.
Thanks again!
I’m not sure of the answer to your first question. I think maybe you can just pick up stitches, but I’m not sure. :think:
If you haven’t bound off that is the way you do it, yes. The 3 Needle Bind Off IS the bind off. 