I've made a little table to handle large and confused fights, I call it the "stray blows" (or something similar, I'm translating it from Italian) chart.
How do you use it?
Each round each character roll 1d100 and add 10.
If he is bigger than most of the people around him (say, a high man among common men) add 5.
If he is really huge compared to people around him (say a troll among men) add another 10.
If he has some distinguishing feature (wears a cool shining armor) add another 5.
Then add the higher between 5 and his (Fate Points)*3.
If the result is 101+ roll on the following chart.
1 Character is hit by someone or something. Receive a random B critical.
2 Character tumbles on something and fall prone.
3-4 Character is hit by someone or something. Receive a random A critical.
5-6 Something hit character on the head! Stunned for 1 round.
7-8 Character tumbles, loose this round attack.
9 Character bump into something and is disoriented. -20 to activity for 1 rnd
0 Something or someone interposes between character and his foe. They're separated and must start a fight with someone else...
The I prepare a set number of enemies (for example 3 for each character) and run them as different encounters, one after another. When PCs defeat all their enemies (or are defeated) the battle ends and I decide who won and who lost.