Well, rules section 3.6.1 says:
British may always use Indian pieces and Leader if a War Party is in the
space during the Battle.
So I would say 'yes' those units are factored in.
Per rules section 3.6.3
If Defending, include all that Side’s cubes, Forts and half
of Active Militia or War Parties
so the 2 active War Parties count '1' in determining Defending Force Level. ...and since both are active, they do NOT give +1 in determining Attacker Loss Level.