What impact does narcissism, not NPD, have on modern parenting?
My answer comes from my own online research from people who may not be professionals, as well as my own experiences and opinion. I am not a professional in NPD nor have I ever talked with one or been professionally diagnosed.
I myself have a few self-diagnosed narcissistic tendencies: I tend to give myself massive amounts of self-esteem (possibly undeserved, but maybe not ;) which allow me to overcome the "fragile and reactive sense of self" by knowing how truly awesome I am. (I am only partially joking)
To put myself on the scale of the given definition, I believe in myself and what I do, I sometimes evaluate myself unrealistically, I can empathize with other people, and understand their feelings and perspectives. I am not devastated by criticism, mistakes, or failure - but I do seem more vulnerable than most, My sense of self can withstand life’s ups and downs and people’s opinions - as long as I'm in the right mindset. I can find a lot of fuel by way of praise and admiration. In general, I would say I lean more than the average towards the narcissist side - but not nearly enough for it to be a disorder of any kind. Or is this an inflated view of myself? I may never know.
I am already a very conscious and mindful person - and I do believe it is the best response.
The parent in the situation at the store is frustrated. She doesn't understand how the child is feeling at that moment and therefore doesn't know how to respond to it in any way other than express how she feels about the situation, her frustration provides an irrational linkage between her "hurrying" and the crying. I can't deal with (this)[being humiliated in public], and its your fault (this) is happening because you always do (this) when I'm in a hurry.
Had she been more mindful and aware, she may have noticed her feelings of frustration and anger. This is an immediate sign to evaluate. "Why am I angry?", "Why am I so frustrated?" "Is it really warranted?" She may have realized she is embarrassed of this happening in public, even though it happens all the time to parents in public. Realizing this is crucial because it means she stops judging her worth by how her child is acting at that moment. Having defeated her irrational immediate response, she can calmly and rationally consider the real situation; try to understand where the crying is coming from and consider what the correct response should be.
That might seem easy for the typical person, but it is incredibly difficult for people with the full NPD. It is a hard enough struggle for me at times, so I tend to believe it. You have to question your own motives anytime you think you might be acting in a narcissistic way. People with NPD may not believe they have the disorder. Even if they do believe, they essentially have to parent themselves before they can parent their child.
I would say the final action that helped me the most was finally accepting how much of a narcissist I can be, and that I don't really want to "fix" it - its a part of who I am. I just don't want to hurt the other people in my life because of it. I can't think of any other way to have reached this conclusion without a conscious and mindful approach. Now, when I encounter situations which trigger insecurity and pain I can usually recognize it and attribute it to my narcissism and most importantly love myself for it. Which, when I think about it, is like turning my narcissism against itself.
This tactic of being conscious and mindful is impossible if they are not even aware of what they are doing, or won't accept the truth. Because of that, it is nearly impossible to "handle" it in a one-time situation for the sake of somebody else's child. For a one-time situation with your own child, I would probably explain to the child that the person was being irrational because of x and that it was in no way your child's fault.
Coming from outside the narcissist - It took many repeated examples of how I was being irrational, needy, and unreasonable, before I even began to believe that something was wrong (not with everybody else) and I might need to find a way to deal with it. At that time I didn't know where the feelings came from or why I felt the way I did with seemingly random little things. However, these examples very nearly drove me away completely because they exactly define what the narcissist doesn't want to hear about themselves - so it may not be "the best" solution to point it out. I am unaware of other strategies unfortunately, so I am not much of a help there. :/
Sadly, in the case where the narcissist is not able or not willing to accept their behavior as wrong, it may mean the best response is to keep away or keep supervision when your child is with a known narcissist so you can stand up for your child or explain any irrational reasoning at a later time. Standing up for the child will result in embarrassment and therefore likely anger in some form from the narcissist - just to be aware.