Walking thru players is blocked on protocols below 8.54 by client. When you press arrow key to walk into player, client won't send packet 'walk' to server.
If you add 8.54 walk thru code to 7.72, it will allow walking thru players by map click [when walk path is calculated on server side], but not by arrow key.
If you are using OTCv8, you can enable it on any protocol using feature Otc::GameCreatureWalkthrough
- of course you must add 8.54 code on server side.