You can't count the times a parent hears that one unwanted word from a child.... "No!"
I know I can't speak for you, but we are truly all the same, and when a child says "No!", there is a certain resistance that arises in us. It is typically taken as an act of defiance, an act against our authority over them. And as parents, we are intended to have proper authority over our children.
But proper authority has nothing to do with any type of demand that we might place upon our child in those moments when that negative manifestation takes place. When we, as parents, act from a place of resistance to what we don't want our child to be doing or saying, we unknowingly create the very thing we say we don't want. What we resist, persists - as Guy Finley (a truth teacher) so eloquently puts it. Or said differently, every action has an equal and opposite reaction.
So, if you consider what I just said and take it into context with a child saying "No!" to a request of ours in any given moment, how can we keep from creating the opposite of what we truly want? How can we properly respond to our child which will truly reflect proper authority and help them and not harm them?
All negative manifestations will fizzle out if they are allowed to do so, but they can't do so if that manifestation is resisted in any way. That resistance to the negative manifestation is typically so fast and so automatic. As such, the most important element to understand is the critical part our attention plays in all of this.
In that unwanted moment, it is important that we reconnect to the present moment, to come back to ourselves fully, in our bodies, and to become aware of the parts of us that want to lash out at our child for defying our authority. We must let those parts of ourselves die by not giving life to them through the use of our attention and the actions they call for. The negative manifestation WILL fizzle out. Said otherwise, that negative manifestation WILL empty itself of itself if given the space to do so.
Then and only then will proper authority from something above this level of consciousness, communicate with us what, if anything, needs to be said or done in that moment. It is difficult because we have so many borrowed beliefs of what should or shouldn't be done or said by a child (or anyone really), and if we want something different for them and this world, we have to let go of those old, borrowed beliefs.
There isn't a set or rules, a certain protocol for life, for what anyone should or shouldn't say or do in any given moment.
The only real protocol is to align ourselves with the only real and proper authority in the moment. We do that through being present and allowing the old, false authority in us to die so that something new has room to enter.
So, why not give it a try and let the old fizzle out so that the new can fizzle in. You've got nothing to lose but an old borrowed belief.