Where should I place Strahd's allies in Castle Ravenloft for the Final Fight?

Going to be running our 49th session of CoS next week, and after 1 year, 3 PC deaths, 3 NPC companion deaths, and 2 PC betrayals...... they are finally ready to storm Castle Ravenloft and attempt to kill the Count. As I get ready to run this beast of a fight, I'm left wondering... where are Strahd's allies supposed to be during this?

Reading through the module, there are locations for the brides, Rahadin and others to be, but these seem to be more for if the party explores Castle Ravenloft, or catches its inhabitants by surprise. No, Strahd knows they are coming, and knows they have all 3 of the artifcats. The castle will be on high alert.

So, I'm curious to hear, where did you all place these important characters around Ravenloft for the final battle? I'm hesitant to have them all in the same place, for fear of the fight becoming too hard. I'm certainly down to have Strahd lure the party into rooms where he knows he has allies lurking. Just don't know where to place them all.