He sounds adorable! How do you let your brother punish your dog? If anyone had the gall to come into my house and not even consult me before disciplining Jack, my Collie, they wouldn't come round again. He has a nerve.
Winny is totally right. I have to ignore Jack, and ask all visitors etc. to do so as well. As soon as he is calm, or goes and lies down, I/they can then greet him and fuss him. It didn't take long for the time between me getting home and him calming down to reduce, as he learnt quickly that calmness=attention.
Fortunately we are quite robust, but we still try and discourage his jumping up. Again, ignore him till he calms. It is SO hard-Jack used to demolish the house when we left him, so when i return to see evrything in its place I just want to praise him to bits! But a dog's mind doesn't work like a human's; if you want to assert that you are pack leader then you must act in a dominant way.
Jack and I were very attached, so we have huge separation anxiety problems with him now. This is why I know how important the ignoring and the dominance assertion is! It helps to spend small periods of time not engaging with your dog, so he understands that sometimes he can't be the centre of attention. Also, try not letting him be the one to initiate play/cuddles.
I hope this helps, he sounds so special. Don't let your brother worry your nephew; he clearly just isn't sympathetic.
Lisa :) x