When knitting projects such as this using various colors of yarn that changes color, I am careful to alternate the joins in yarn. While working, continue alternating between the two skeins until approximately ½ of each of the skeins are used. Break the yarn of Color A and spit splice a new skein to the yarn tail, reserving the remaining yarn. Continue knitting until the end of your project, adding skeins of yarn as needed. When finishing the project, as you come to the end of Color A's yarn, spit splice the remaining ½ skein previously removed. Using this trick will make the joins almost impossible to detect. If the yarn ends that are spliced are similarly colored, the join will be invisible. I used this technique when making Technicolor (the sweater pictured below) - and used 12 different colors of Noro Kureyon for that project.