I have an "old style" Mega Tree, 16 strands each of Red, Green, Blue and White.
I used to model them as four separate trees, but instead modeled it as a 360 tree with RGBW.
It makes things easier to program, for sure. If I do a pure R or G or B or W, that is exactly what I get.
If I use Purple (Magenta?) it will light up Red and Blue strings.
But, your strings need to be wired sequentially in RGBW order to work right. 64 consecutive channels for me.