Merging traffic

[NDORFN]

So somehow I managed to get a Scaleroad traffic ribbon to merge with another. I laid some road with an intersection where the merging road curved into the main road using the 'Snap to track' option then added traffic ribbons using the offset option set at 0.1m. At first the cars on the side road dissapeared at the merger point with the main road, but the next day (hense a restart) the traffic was merging. The cars on the side road just slotted in nicely with the main road and carried on to the end of the main road ribbon (which is great because it's conveniently out of sight). Here's the problem... I can't for the life of me get it to happen again. Does anyone know how to get it to work (intentionally that is) ???