First of all, you really should add a 1.5 mm dermastamp with 35 needles to your dermarolling sessions. A combination of a dermaroller and a more targeted instrument (such as a dermastamp) proved to be the most effective.
During the same session (every three weeks), stamp the scars and then roll them.
If you have too many scars, you do not have to treat them all in one session. You can treat one cheek, as soon as it heals, treat the other, when it heals treat the temple etc.
If you have the rolling type of acne scars, add our suction pump because this type of scars is usually tethered to the underlying structures and the pump will help releasing the fibers.
Scars are a difficult problem and various approaches and a little improvisation is often needed to achieve results.
If you also have the boxcar type of acne scars, you can for example try inducing intensive peeling by applying the A-Ret cream (we sell it) right after microneedling (it stings and it irritates the skin). Do a test patch first to see how your skin reacts.
You can read about it in this forum thread (reply 25 from Cesamaddictaol and my reply #26):
https://http://forums.owndoc.com/dermarolling-microneedling/evenly-spread-acne-scars/15/ There is no problem with treating scarred and non-scarred skin at the same time because the scarred skin has tendency to level up to the surrounding skin, no matter whether the surrounding skin is treated or not. You should however concentrate on the scars as much as you can because scars really need intensive treatments and it sometimes takes a long time to improve them.