New to UV



I am new to UV and I am practising how to unwrap an object. My question is, how can I stitch UV-shell A to UV-shell B? I can only stitch one edge and the rest of the edges can’t seem to be affected by the “stitch together” button. The sew button works but it will distort the UV (see image 2) which I don’t think is nice.

Thank you in advance.

Image 1

Image 2