Here is the easiest way and the way I teach all the people who play in the league I run when there is multiple all-ins.
First off, nobody should have pushed all the chips into a big pile. All the money should still be infront of each player even though three people are all-in. We deal out the cards before we even care about who has more chips.
I then look at the big stack to see if he wins the hand. If not, then we go down to the short stack and work our way up. You then match that players stack if he wins the hand. You continue this until all hands have been dealt with.
This method only works if you don't splash the pot with the bets before the hand is dealt out.
example: nobody improved with community cards.
Player A has AA 10k chips
Player B has KK 15k chips
PLayer C has 22 2k chips
You look at big stack. Did he win? no.
Look at small stack. Did he win? no
Look at middle stack. Did he win? yes. Player B matches what player A has in chips and player A collects the short stacks chips.
player A KK 10k chips
player B QQ 50k chips
payer C 33 100k chips
did big stack win? no
did short stck win? yes. He will then get 10k in chips from everyone in the hand.
did middle stack beat the next part? yes. He then gets what he has remaining in front of him matched by the big stack (40kin chips)