Normally, questions are not alternately shared, at the discretion of the chair, for the second round. Or, at least, that was not how it was done in the committees on which I have sat. The second round starts again with the official opposition, followed by the Bloc, then the government, then the NDP. I think that this is a fairer way of proceeding.
The order could be at the discretion of the chair for the third round. This would give you a certain latitude for determining who got the floor.