Ultimately I had to remove this mod. I was not expecting, but could somewhat understand, belts marking flow spots into chutes and loaders as spill points, since it was likely not something that would have been accounted for when you originally made the mod. But belts flowing into the side of belts being marked as a spill point? That's completely vanilla and entirely unlooked for behavior in this mod and not shown at all in the description or example pictures. I realize this mod is old and hasn't been updated in a while, but is there any chance at all you would be willing to allow us some control of what counts as a spill point in the settings for this mod?

Side loading will only spill if you try to side load more than will fit onto the target belt, like any other spill scenario. Or, at least, that should be the case. If I work on this mod again I might try to make it optional, but probably not.