How can I make the wiggler parts show up on my map?
Solution 1:
They show on the map automatically, after Mario becomes aware of their location (sort of). If I remember correctly, if you get a wiggler part, but it then runs of to another level, you can see where it ran off to using that marker.
This would help if you looked away from the screen in the short cutscene of the part running of, or forgot where it went.
You can’t “make them appear”. You have to find the parts.