Planning on knitting Bernat Baby Jacquards - Ruffle Edge Blanket. The border is knitted separately and then sewn onto the blanket; the instructions read:
“Beg at center of one side, sew shorter edge of Border in position using flat seam. Sew side seams of Border.”
http://www.knitsimplemag.com/node/80
Scroll down to edge-to-edge seam. That should help.