PP/OP, I would make any such "don't put me with..." or "place me with..." requests in general statements. Such as, "Sally needs children who provide a good example BECAUSE she gets distracted if X, Y, or Z". Or "Sally does not do well with distractions such as A, B, or C." Or if Sally doesn't get distracted, but gets something else... you get the idea.
I would not mention any children by name, unless both parents are making a request to not place their kids together (and approach it with "Our children are too mischievous together and we do not want to cause classroom disruptions. We request that they are not placed together for next year.")
If you are going to make any requests, in the spring you should speak to the current teacher to see how she thinks things are working out and if you have learned any particular classroom situations that work well or poorly.
The first week can be hard. Keep your chin up!