Picking up new stitches

this is what I am making (photo is mine)

It’s a cloth diaper soaker with a skirt attached

but I do not like how visible the seam is where I picked up the stitches for the skirt part.

what I did was purled a row of stitched while knitting the soaker (in the round) and then went back and picked up the top bump of all the purl stitches and knit those to make the skirt part.

The one I am currently knitting is not as obvious because I paid really close attention and knit a lot looser than I normally would have, but it still is not perfect.

What would be the best way to attach something like this to something knit in stockinette stitch

I just tried picking up the stitches directly onto the St st with no row of purls and it looks smooth. The trickiest part will be being sure the ones you pick up are all in the same row, but you could probably mark them somehow. If you can’t eyeball them you could use some sort of quilters pen that disappears when it gets water on it. Or even run a line of sewing just one side of the ones you need to pick up (then take it out). Try it on a swatch and see if it doesn’t work well for you.