Effective immediately Harness Racing New South Wales (HRNSW) Stewards will interview any Trainer that has 2 or more horses in the same race regarding the intended tactics to be adopted.
It is not intended to make these tactics public, unless they are determined by the Stewards to be a change of tactics to any of the horse’s normal racing pattern.
Any Trainer that has 2 or more horses in a race is required to report to the Stewards no later than 40 minutes prior to the advertised starting time of the race.
From HRNSW web site.

This rule should help trainers that are doing the right thing, it is better to tell the stewards before the race that you are going to hand up to a stable mate than to have to explain why you did it after the race. The rule should also help stop team driving, if that is currently happening.