answer - Viewing the Map.

[elizabeth1603]

No: HPFGUIDX 60608

I also believe the Marauder's Map only shows people who are moving. I think 
the books always say the people on the map are pacing or climbing stairs, 
etc. The only problem is that when Harry was trapped on the stairs in GoF, he 
was afraid Snape would look at the map and see him standing there, 
suggesting that people standing still would show up. On the other hand, Harry 
wasn't looking at the map, so he couldn't be sure he would show up. 

It's a good question. Another suggestion, besides the excellent ones already 
offered, is that Fred and George didn't know who Pettigrew was and didn't 
care, so they took no notice of him.

"Elizabeth"