Help with lace pattern!

I am knitting a lace vest. I’m an intermediate knitter.

I cannot seem to get the lace pattern to line up following the armhole shaping/decreasing.

Armhole shaping/decrease:
BO 4 sts at beg of next 2 rows—59 sts rem.

Dec Row (RS): Sl 1, k2tog, work in patt to last 3 sts, ssk, k1—2 sts dec’d. Work 1 WS row even in patt.
Rep the last 2 rows 4 more times—49 sts rem.

Lace pattern: ( ) Repeat across row

1st Dec row(RS) M / - \ yo K K (K K K yo / - \ yo K K)
1st WS row: P P K P P P P (P P P P P K P P P P)
2nd Dec row(RS) P P \ YO K YO / (P P P P P \ YO K YO /)

I have tried this many times and my pattern hasn’t lined up yet.

The instructions say for 1st Dec Row–first stitch, M (rather than yo to add a stitch, making a knit stitch between two)

1st Dec row: Do I make this stitch (M) before Slip 1? then do a k2tog?
Do next row in pattern-I can do this row.

2nd Dec row: Since I’ve BO 4 stitches, do I count the \ as two stitches, so I start with the yo-do I yo and then slip that stitch, then to do the k2tog, do I make a yo so the k2tog would be the K plus a added yo?

To continue the lace pattern, do I count the M stitch or YO as a stitch that was decreased when counting the pattern?

I hope you understand my questions and can give me some advice.

Hi and welcome!
For the M or make one increase, do that after the slip one and the k2tog. The slip stitch is an edge stitch and the k2tog is part of a line of decreases.
Usually it’s best to read your knitting in order to figure out how to start the lace pattern repeat. I look to the previous rows (assuming the lace pattern is used earlier), and count backwards to see where to start the lace pattern.
Sometimes, you’ll have to substitute stockinette stitch for the lace pattern because you can’t work a full or even partial repeat. Then when you can begin a repeat in line with the earlier pattern, do so.
Can you give us a pattern link or a pattern name?

The name of the pattern is Angelica Vest on allfreeknitting. (I tried to add the link to my question but I wasn’t able to).

So after binding off the 4 stitches for 2 rows, and then doing the slip 1 and k2tog, I continue the pattern as before and I don’t start on the stitch after those stitches are decreased. I understand about decreasing.
The lace pattern is a total of 12 rows so it is not a pattern that is easy to count in order to line up the pattern.

Very elegant vest.
Continue the lace pattern on the same rows as the armhole bind off. Don’t skip any rows because of the bind offs or decreases.
Even though it’s a 12 row pattern, you can see where the eyelet yarn overs are placed. Use that to predict where a yarn over should go on the current row. Do the slip stitch and the k2tog and then count back or name the sts to the next stitch on the needle. That way, you’ll be sure to start the pattern correctly.
The note at the beginning is a reminder not to start in the middle of a repeat if you can’t work an increase and its corresponding dec.