Dear Confused and Disappointed,
You have every right to be upset and worried over your son's behavior. You've already raised two adult sons and are still raising your 14 year old and although no matter how old one's children are, parents will always worry but the way I see it, while all 3 of your sons were living at home, you did your share of worrying who was staying out until what time, what they were up to, etc. You shouldn't have to deal with that now just because your adult sons are living with you at the moment.
You are very generous and understanding to allow them to move back in with you and the ground rules you've set are appropriate and reasonable. You pay the bills in the house and it's only fair if they're going to be living there, eating your food, etc. that they contribute to the household expenses.
I think personally that if your 19 year old doesn't think he has to follow the rules of the house, not only are you going to feel used and taken advantage of, this will also cause more stress than you need at this point of your life with so many new changes ahead of you. Also, if your 19 year old is allowed to get away with staying out until all hours, not bothering to call and sneaking in and disrupting your sleep, which is undoubtedly compromised on the nights you're worried about what he might be up to, this will take its toll on yours and his relationship and also that between him and his brothers. You're right to be concerned about the influence this behavior might have on Zac, who's at a very impressionble age and no doubt looks up to his big brothers for advice and guidance. You don't want Zac to fall into the same course of behavior. Also in regards to your eldest son, you and he have the opportunity now that he's with you, to grow close and to nuture your relationship but if your 19 year old isn't held to the same rules and expectations of the house that your 22 year old is, that will only lead to arguments, resentment and accusations of favoritism.
Now is the best time to nip this in the bud, maybe in the form of a family discussion where rules and responsibilities are again emphasized, down to specific chores/roles of each son and what your expectations are of each of them. Obviously Zac doesn't work and pay room and board but if he has certain chores to do, maybe getting everyone together and going over the ground rules would be a good thing so everyone knows where they stand and what's expected of them and also it might create a healthy forum for anyone to voice any opinions or concerns they might have about anything. Also if it were me, I'd take your 19 year old aside in private and have a talk with him and explain that his behavior isn't acceptable and must stop immediately if he expects to stay there.
I can't speak from a parent's point of view but your 2 adult sons have moved home to get back on their feet, get jobs and regain their independence and going out and partying every night wasn't part of the agreement, if he wants to do that he has no right bringing you into that world and causing you worry and stress. Maybe give your 19 year old a set amount of time in which he must come up with the rent owed as well as the cost of Zac's bike and if he's not able to pay it, he'll have to find someplace else to live. If he were in an apartment and not working or paying the bills, the landlord wouldn't be as understanding, he'd be kicked out in the street.
There's nothing wrog with hanging out with friends and having a good time, that's what weekends are for, your 19 year old could easily find a job and still have time to have fun with his friends and also contribute to the household and show you the respect you're entitled to and he needs to understand that. You're a great mother, there's no question about that, if a kid of mine needed anything I'd give anything I had for them but they also need to be willing to help themselves. You're about to embark on a new and very important chapter in your life and you don't need the added stress and disruption in your life. I think maybe if your 19 year old had a set date in which he needed to pay the rent and compensate for his brother's bike, that would force him to take some responsibility, it's either that or find someplace else to live. 19 is very young and many people that age don't have a firm grasp on their responsibilities and obligations and many seek even to escape them but if allowed to get away with things now, he'll always expect a free ride, from everyone, and he'll never grow up and accept responsibility. He'll be a kid all his life and as such, will always come running to you to pick up the pieces when life gets too complicated.
You've met him in the middle, you've allowed him to move home so he can get back on his feet and make a fresh start, you've done your part, now he needs to do his and live up to the rules you've set down. You're not at all asking too much from him. He can have the best of all worlds if he gets a job and contributes to the household expenses and acts responsibly and doesn't cause you worry and he can still go out with his friends on the weekends, that's a very fair deal and he needs to realize how lucky he is to have it.
You have enough to deal with at the moment, when Waz moves over there, you don't want a war zone going on and your sons should be thrilled that you've found someone who loves and cares for you and treats their mother like a queen and they should do everything in their power to contribute to a functional, positive household.
I personally would sit all of the boys down and have a family discussion about responsibilities and also have a private word with the 19 year old and let him know there will be consequences for his actions. If he expects a free ride from you, your 22 year old will too and that will set the wrong example for Zac and they'll all be living with you forever lol, now that I've scared you lol!
You're not being unreasonable, you've been upfront with your expectations, now they just have to be made to stick and everyone needs to be in agreement with them.
Good luck, the sooner this is dealt with the better for everyone involved, it's a huge change having all 3 sons under the same roof again, this along with your new job and plans for you and Waz, your sons need to realize how much you've sacrificed for THEM, now it's time they support YOU and your needs. You're allowing them a second chance to get their lives back, it's only fair they return the favor and do their part to support you and think about your future happiness.
Good luck!!! You're a great mom, don't forget that, and though it's easy to do, don't cast your own needs aside, it's not selfish to put yourself on your own priority list, make the room.
Let us know how things are going!
Love and blessings!
SheCat