NFHS states that assistant coaches can't stand. However, if the assistant coach is causing no problem, i will allow them to. Here is an example of the frustration that referees and coaches have when one won't hear out and listen to the other. I believe it is a 2 way street, you make mistakes as do I.
last night i was working a 7th grade boys tournament. During the first quarter, I call a travel on team B for taking 5 steps! The coach barked about it for a while, then during 1/2 time, the coach comes over to "confer" with me about a travel call. I told him his player couldn't take 5 steps, and elaborated on it. He told (I use this word lightly, it was more of barbarically screamed
) me the same play happened last night in the bucks game and those refs let it go. He told me that 6 steps would be a definate travel, but 5 wasn't. I showed him the rule book and he still didn't believe me, but that added to the fun of it, it was humorus
if you want to approach a referee go to them during a break of play, ask them rationally why they did what they did, nod and give them the impression that you really are listining (you'll get farther this way), then calmly explain you side of it, see what they say, but if they don't see it that way, then leave it.