One kitten only wants to eat out of the other's bowl

So, I have been transitioning my 4 month old kittens to meal times rather than free feeding them.  One kitten, Hobbes, is at least half a pound bigger than the other, Isabel.  I'm trying to make sure they each get the right amount of food for their weights.  The first week was fine.  Each kitten chowed down at their own bowl and generally finished the meals in two or or three passes within an hour.  Suddenly, last night, Isabel turned up her nose at her kibble and ran to the other side of the room to wait for Hobbes to walk away from his first pass.  Then she swooped in to finish Hobbes' bowl.  Same thing over the next few meals.  Hobbes has been going back to eat some of Isabel's food a bit later, but I'm worried that neither of them is getting the right amount of food.  What to do?

You should try feeding them in separate rooms with the door closed so that one cat can't eat the other cat's food.  If they take too long to eat the food and you don't want to separate them for a long time, you can "train" them to eat the food quickly by picking up the food after a certain amount of time (say 20 mins).  They'll learn that the food won't be available after 20 minutes and will start to eat it all.  Otherwise, give smaller frequent meals, so small that they'll eat it all quickly, and the door can be opened again.   

Our last pair of siblings would routinely swap bowls back and forth. So long as both kittens are growing well and look and feel healthy it really shouldn't be a problem. So long as Isabel isn't going hungry I really wouldn't be concerned. Remember that boys are generally a little bigger than girls anyway :catguy: