can piping be the 3rd color?

I am in the middle of living room makeover. My 1944 cape cod living room/dining room is painted a soft yellow with white trim. White mantel and white 2" wooden blinds. My hardwood floors have been rescreened. My sofa is being reupholstered in a buttery yellow. The other colors I want in this scheme are a rasp/cranberry red, blue(sky) and of course the yellow. The sofa fabric is a chenille. I can not go that pricey w/ the other pieces so I am shopping at the Mill End Store in Portland, OR. So the selection is limited, as compared to shopping at the upholstery shop. I have a channel back chair and a chair that goes w/ the 1935 sofa to cover. I purchased a small check in sky blue & white for the channel back; 4 yrds upholstery chintz for $26. I have found a fabric for other chair that is my red w/ yellows and soft greens-florals- but no blue. I am wondering if I could pipe the red,yellow, green floral in the same blue as the chintz and pipe the blue chintz fabric in yellow or red and that way the blue would tie in or am I "forcing" the blue?