The biggest kitten from my last (foster) litter would nurse with his arms spread wide, keeping the two nipples next to him free of another kitten. I don't know if he would nurse from the nipples later or not! What a piggy boy! I did have one of the litter who failed to gain weight like the others, so I supplemented with bottle feedings, and now he is doing great.
Congratulations on the healthy babies. You are going to see a LOT of fighting among the kittens as they grow. Sometimes they bite hard enough to make the other kittens cry! It is all part of the learning process!