to the amusement of the onlookers as he gave a running commentary to the DOG about the PEOPLE in the ring. Quite funnyAh bless, maybe you could elaborate on this as in giving him a dictaphone to play judge. He may enjoy that for a while.
Apart from the advice already given...........
It's difficult with children as one minute they can be interested the next they have moved on and find it boring, my eldest loved everything that I did, if mum loved it, so did he and he had a real interest for many years, my youngest was interested to start with but then became bored and restless so I didn't push it and he stopped going, I guess that is what you will have to look out for, you can't force an interest and it
does have to be an interest for him too, mum's are allowed a hobby, children don't get upset about that or need to be included in it, as long as all children get plenty of one to one time then they don't care that mum loves to show and has her dogs, they really don't.

So don't feel for one minute that he will think it is a contest of mum and the dogs verses mum and me.
However, if later on he is made to go somewhere he doesn't really enjoy then that will feel like the dogs are more important than him, because you are making him go somewhere he would prefer not to,
that would cause resentment of the dogs and you.
So, IMO if he is happy then give him the role of helping you, ask his opinion on things to involve his interest, (also this shows a real interest) he may be interested enough to show himself and you may have a star in the making, but be careful that he is just not copying mum with role play with no real interest because that will fade pretty quickly so keep an eye out for that, if he does get fed up then leave him at home and don't feel bad about it.