Not sure why this isn't a thing yet, but why don't they show up on ctrl A big map, but burrows are? Cave Passage can't be destroyed or despawned right? Even with teraforming they can't be removed right? That aside they should appear in natural section. Don't see any issues with it as it will be convenient for everyone.
Also let us edit on the big map which icons we can see and which not, I know there are for all icons on big map, but make it adjustable just like minimap icons. Not asking to import every icon from minimap for big map or what is the term for it, but at least let us choose what to see as I have no use of seeing burrows personally.
So yea please, pretty please add cave passage icon and make us choose which icons we want to see on big map and which don't want to see, because full zoom out is a cluster mess.