Decrease on ribbing? help

I consider myself a beginning intermediate knitter…every once and a while when reading through a pattern before beginning I find something that I’m not exactly sure how to go about doing. in the sweater pattern I’m currently doing, the directions for the neck shaping go like this:

working in k3, p3 rib, inc 9 sts evenly across sts on each side

How do I do this and still maintain k3 p3 ribbing? I may just be imagining this, but won’t an inc in the middle of a rib make that rib a k4 rather than k3? I guess I’d just like to get an idea about this before I dive in; I’m rather paranoid about making mistakes! thanks!

Should your title say increase instead of decrease? INC means to increase.

I would increase the way you are describing. For what you are describing, the increase could be done on the knit stiches by picking up one in between the knit stiches. Does this make sense?

The more I read my response to you, the more I’m questioning if I have that right. What are you knitting?

Is the next row after the ribbing the first of a stockinette section? Very often sweater ribbing is increased in the last row and stockinette starts. If that’s the case, you don’t have to continue the ribbing, so it won’t matter.

whoops! Sorry, yeah, it is an increase, not decrease. And no, the next part of the pattern is not in stockinette. I’m working the shoulders of the back of the sweater, which are completely in k3 p3 ribbing. I understand dec or inc on the ends of a rib row, but I just don’t get how it will work in the middle…just seems like it will cause a k4, p4 rib the next row, then a k5, p5 rib! maybe I’m overthinking it and it will make more sense when I get there.