Interesting, I was unaware of Intersection Groups & will give that a go as a preferred method, as I would rather not change the reference line and would never create a marginal gap. Thanks for your help & suggestions

I also have issues with junctions, stud wall against brick. different material. Different junction priority, and for some reason it wants to kick the bricks into the stud wall, and put a line break in the break wall. Image A and B show the reference ...