Use of two yarns of different composition

I am making a baby blanket. I started it with yarn that was 100% acrylic and is variegated, going from white to yellow to blue to coral back to white, etc. I became bored with the pattern I was doing (K2, P2, K2, P2, etc., etc.) I did that for about 8" (blanket is to be about 29" when finished). I switched to another skein of yarn--same weight (a "3"). I thought it was the same material. However, it turns out that it is 60% acrylic and 40% nylon (instead of 100% acrylic). I knit about 2 1/2" with the 60/40 skein (in a different color--a soft blue. Baby is going to be a boy but the parents want "gender-neutral" items). I'm noticing that the blue "stripe" is (slightly) puckering the stitches below. Will this resolve when I block the finished piece or do I need to remove it? The puckering seems minor. I have also knit a few more rows of a star stitch pattern and then the beginning of a moss stitch pattern after the 60/40 yarn. Both the star stitch pattern and the moss pattern are back with the same yarn that I used for the first 8". I'd like the make another "transition" block after the moss stitch possibly. My intent is to 'finish up' the blanket with the same pattern (the K2, P2) that I started with. It's turning into kind of a "sampler" (stitch-wise) blanket. I seem to be making up my own pattern as I'm going along, but I do want it to look attractive in the end and not like a "mistake" baby blanket.

Thank you for your help.

Claire J.