Need advice dealing with f'in four and/or jealousy - struggling with punishing, teaching values

Hello parents!I feel like I need some help.My 4 y.o. has always been very energetic. Overall, he's a good kid. He's very loving, and demonstrates empathy when someone is hurt or sad. I'd say he's probably your normal / average 4 years old kid.He's also a charmer, a class clown, and a master manipulator.Ever since he's turned four, he's been a lot more difficult with us. He challenges everything, tests the limits, tries to impose his will, screams at us when we refuse to give in to his ways, etc. Having read about the "f'in four" period, I know this is normal, and to some extent we are able to get through to him by talking to him. It's not always easy, but that's not the part I feel is problematic.The issue that we're struggling with is that he is absolutely out of control when anyone else is present. Whether it's his friends or family members, he immediately disregards all the rules and completely goes rogue. He's bossy, arrogant, he lies, he throws tantrums, he hits us, he won't listen to anything and we simply cannot get him to behave ever.It feels like a serious issue because his behaviour has caused other kids his age to be uncomfortable around him. His cousin - 1 year older, whom we know our son truly loves - no longer wants to see him, because he doesn't feel that our son can share and play constructively with him. Moreover, he feels that our son always purposely gets him in trouble and throws him under the bus every chance he gets.And I know that to be true.We tried many things, mainly along those two lines:We tried talking to him calmly and conveying that his behaviour hurts the people that he loves. It felt like it resonated with him at the time, but that didn't last a minute when the next visitor came over. We tried reading books about sharing, friendships, etc. and it has no effect whatsoever. We also designed and implemented family rules, involving him in the process, and he forgets all about then whenever he's excited.We tried punishment - he was recently without TV and dessert (his two greatest loves) for more than a week, but generally speaking punishing him is ineffective. (We experimented with different punishments.)I should say - and this is probably very relevant to the situation - that he has a 1 year old baby sister who obviously takes up a lot of our time and attention. We are very mindful however of being equitable and not neglecting him when taking care of his sister. We are also very mindful of not changing his routine as much as possible and giving him extensive 1:1 time.At this point I don't know what else I can try. I don't even know where to begin.Does anyone have any experience with a similar situation? Can anyone point me to any relevant resources on the topic?Thank you! via /r/Parenting https://ift.tt/2CIMafC