Increasing on a knit purl row

I am knitting a sweater and the stitching is knit 1 purl 1. I have to increase every 4th row at each end. Do I do it at the same stitch on each row to get it even? Any help would be greatly appreciated.

You can inc 1 st in, work the first st, M1, then continue the pattern to the last st, m1 and work the last st. To include the new sts in the pattern, just knit them as they would be for the next or previous st. Leave the edge sts in stockinette for seaming.