Shaping the shoulder and shape back button border help

I have shapped most of the shoulder thus;

cast off the rem 13 sts (this was what i had left from doing my 3 decreases and working the next four rows) DONE

with RS facing, slip centre 12 sts onto a holder, rejoin yarn to rem sts, k to end- DONE

Dec 1 st at neck edge on next 3 rows (13 sts)- DONE

Work one row, ending with WS facing for next row- Now i have done this but only on the sts i was working the decreases on, the 12 centre sts still sitting in the holder, is this rigt or should i have done them incl the 12 sts on holder?

The way i have done it, i have left rhe 12sts on the holder and they are still there at the moment, so in my head this next bit is going to be worked on the sts i have just decreased AND the 12 centre sts (which look like a row down) and in myhead this looks right to give me a button hole??

Then after i have confirmed the above little bit the next bit, i think i get but want to check;

shape back button border

(WS), P2, inc next st, (P3, inc in next st) 2 times, P to end 16 sts.

Can you adv me what this instruction means and also tell me why there is the bit in brackets, is it because i am P3, inc in next st twice?

i feel like i am asking to much questions so apologies :aww:

Thanks guys

There’s never too many questions when you’re doing something new to you, so don’t apologize.

You’re right the (P3, inc in next st) 2 times, means to repeat twice, so you would p3, pfb, p3 pfb.

The second shoulder should mirror the first shoulder so the 12 center sts stay on the holder while you shape and bind off the shoulder. You can read ahead and see when you need to work those center 12sts, perhaps when you pick up for the neck band or collar.
The next part, the “(P3, inc in next st) 2 times” has the brackets so that you know what sts to work 2 times, just as you thought. So you’ll (WS), P2, inc next st, P3, inc in next st, P3, inc in the next st, P to end 16 sts.