
I am no expert, but have had similar happen with my bunch.
I put it down to the younger to trying to dominate the elder dog, to me she is trying to become the Alfa in the house regarding your older boy.
My older girl still roles the roast with my younger dogs, she will take their treats from them and store them next to her and if they show any sign of wanting them back she will growl at them, she has never 'gone for them' but just gives a warning growl.
I decided that I could not live like this as although she did not show any signs of aggression towards us humans with food, treats etc: it was still very annoying when she did it to the my other dogs!
I made sure that I showed her with my body language that I was boss, standing over her upright if she decided to growl at the other dogs over food, and if that did not work I then took the item away from her, as to claim it as my own and give it to the other dog, and sit by the other dog to show her I was allowing the other dog to have the treat and she was not to touch it, you need patience, but believe me it does work!
Now my dogs can have treat again, near each other, without problems, and when its feed time the first one to finish will sit and wait for everyone else to finish then they will calmly check each others bowls in case they had missed a bit of food!
It is also quite funny to watch them drinking, they sort of like form a que! and wait for each other to have their drink then the next one goes, and so on!
As for her jumping up at your older boy, again I believe this to be domaninance or maybe trying to erge him to play with her, I have had this too, and have normally left it to the older dog to tell the younger one off it they are annoying, but sometimes I have had to intervene and stand over the younger dog and say 'Hey'
It again has worked with my dogs, but I suppose it all depends on the individual dogs.
xx