Help deciphering a pattern

I’m a basic knitter and I purchased a pattern today for a layette afgan that looked like something I could handle. However, I’ve run into a problem with the pattern already. Following the pattern I have 163 stitches on my needle after 3 rows the pattern reads:

ROW 4: K2, P2, K2: * P4, P2 tog tbl, YO, P1, increase, P1, YO, P2 tog, P4, K2; repeat from * across until last 4 stitches, P2, K2: 172 stitches.

I’m having problems figuring out the “increase” above. The only type of increase they refer to in the instructions is a YO, so I’m not sure if the “increase” should just be another YO or something else. I’ve worked this row several times using a YO but I keep ending up with the wrong number of stitches.

Any tips? The pattern is called Lilac Loveliness ing the book Our Best Knit Baby Afghans published by Leisure Arts.

Thanks!

The increase should probably be a m1 or pfb, the YO in this pattern is to make holes for the lace and they’re offset by the decreases. I think it should be a pfb since you inc by 9 st so the pattern is repeated 9 times. There are 10 sts not repeated at the beginning and end, so the pat rpt is over 153 sts and dividing that by 9 is 17 so that’s how many sts each repeat uses. There are 16 sts in - p2, p2togtbl, p, p, p2tog, p4, k2 - so the increase has to use a stitch which would make it pfb. The YOs don’t use a stitch, they just add a new one between two others.

Thanks so much!