I may have your solution. I did a Log Cabin block that came out curved in the middle instead of straight diagonal and I wanted "dots" at those junctions to make the curve obvious. Let's say you're doing a two color LC block - red on one side, white on the other, and you want blue dots on your diagonal points. Paper piecing this LC, put your red strips in where they belong and for your white strips use a modified strip. (this is hard to describe without drawing) Let's say you've cut a panel of white that you'll cut your strips from. Lay it horizontal. Across the top, the length of the panel, sew your blue strip. Now when you cut a strip of white it will have a blue end. When you lay that into the pattern match the seams. Sew it in as you would any other strip in paper piecing. You'll end up with another color in your block. In your case, that 3rd color (or other color) can be attached to the strips that are upright in your pattern. This sounds so complicated. PM me if you want more info.