I just stood right behind my son while he worked with Harley when they started out (or if we are working on something new). He would give the command and I would have to repeat it myself while standing behind my son with my hand on his (we also use hand commands) and the treat in my sons hand. Eventually we got to the point where I would just say "Haarrleeey.." with a 'look' if he didnt listen to my son and he would then do it, that turned into just the 'you had better listen to him' look with my eyes to now he will listen to basic commands from my son (whos now 4) without me being anywhere in the room (I can ask my son to let the dog outside and he calls him "Harley come" then invites him into the kitchen "Harley here" then has him sit at the door "Harley sit" then "Harley wait" and opens the door before releasing him to go out the door with "ok"). It took time, and we didnt/dont work on it very often, just now and then my son will get the bug to do something I do and I will always just make sure Harley listens to him.