It's okay.
My experience with subcommittees is that if they aren't representative of the percentage of the main committee, then they are basically a waste of time. So you need to have a microcosm of the macro committee. That would mean the same percentage of representation on the subcommittee.
Otherwise, you would be the tie-breaker, Mr. Chair. The way it's set up, if there were two Conservatives, one NDP, and one Liberal, which are the vice-chairs, it would be the chair. So you would need one more Conservative in order to have a proper representation of the main committee.