You'll need to put in a formal request in the
Grievance forums. Make sure to read the rules.
Also, you might note [LORE]Disarm[/LORE]'s description on LORE. In the future, before taking feats, skills, etc. Research how they will work in Layo by visiting LORE so you won't have to go back and fix things after the fact.
As for replacing disarm, the knockdown feats seem appropriate.