Yarn Substitution Question

I found an old afghan pattern that has multi-colored borders with solid color seed stitch between them. You are supposed to use 2 strands of sport weight yarn held together.
There are 4 different colors in the border and the colors change often enough that you can carry the yarn up. But I just can’t imaging keeping double strands of 4 different colors from getting hopelessly tangled.
So - my question is: as long as I match the gauge, shouldn’t I be able to use a single strand of worsted?
Or does anyone have any other suggestions? Thanks!

Sure you could. And you don’t really have to worry all that much about the gauge being exactly right since it doesn’t have to fit anyone.:shrug: