I guess I'm not understanding this question. Maybe it's just me. It's the kitchener stitch thing that's throwing me. Are you wanting to graft garter stitches using the kitchener stitch, as in seaming them together with an invisible seam? Many times this is done for things like the toes of baby booties that are knit in garter stitch.
Here's a great video that explains how to do kitchener stitch on garter stitches and make it blend in. This is Russian grafting. It's a cheater kitchener stitch done with a crochet hook. I like to use this to close off the tops of mittens knit in stockinette stitch when I just have a few stitches left. It leaves a tiny bit of a ridge, but appearance isn't that much of an issue in this spot.