You need to let your girlfriend deal with her child. Kids can be especially annoying at that age, I know. As a side note: I think it is very sad that you see the boy more than his own father.

I have a couple of follow-up questions and suggestions.

First set revolves around the jobs. Why is your SO (significant other) working two jobs? Is she getting CS (child support) from BD (bio dad)? Are both jobs lower wage? Can she not get a higher paying job? Does she LIKE working two jobs so she doesn't have to spend time with her "cunning and manipulative" kid?

Second set revolves around BD. Does he only want EOWE (every other weekend) custody? Could he have more time if he wanted it? Does he want move time? Is your SO the one preventing him from seeing his BS (bio son) more? Does he have problems that make your SO want to limit his contact with BS?

Third set revolves around you. When you say "dominance", do you mean that you are trying to control everything that goes on in the house, or that you are just trying to get your SS (step son/partner's son) to mind himself? How are you asking/telling him to do things? Does your SO back you up when you tell him to do something, or does she come back with (in front of him), "oh, he is just a kid, back off him a little"? Do you want children of your own? What future do you see with your SO? What benefit do you get from being with her?

Now, these may seem like a lot of invasive questions, and I'm not necessarily saying you need to answer them on here for us. But they are questions you need to ask YOURSELF as you move forward. I am going to try and give you some advice based on some answers to some of these questions, so if I don't hit it right on the nose, answer the question on here and we can try to be helpful.

Onto actual advice: I have two SSs who I have lived through older childhood with, and the behavior you describe seems fairly normal. Not okay. Not to be tolerated. But normal. I feel like 80% of my communication with them is telling them to do something that they should already know needs to get done. Part of their behavior is actually forgetting. Part is hoping that if they don't do it, someone else will do it. Part is hoping that if they don't do it and you didn't remind them that they can later blame it on you.

IF your SO allows you to discipline (and we'll talk about that in a minute), then start setting your SS up to be responsible but allowing consequences to fall where they may. Example: If an agreed upon punishment for not picking up clothes or not turning in homework is losing video game time, then remind him once to do something, set a time limit, and check in that time frame. Not done? Punishment happens. It usually a good idea to remind kids of the punishment WHILE giving the reminder and time frame as they are just as likely to forget that a punishment exists as the thing they are supposed to do.

Now, all of this assumes your SO allows you to discipline her BS. There are a lot of thoughts on this board about the role of stepparents or those dating parents and their role in discipline. My personal thoughts are that ANY adult should have authority to discipline a kid who isn't doing as they are told, but the PARENT sets what that discipline is within their own home. I know what my DH (darling/dear husband) will allow and won't allow as far as punishment is concerned, but he trusts me to be able to dole it out as I deem necessary. Your SO either needs to allow you to discipline when she isn't around OR she needs to be around more. The only outcome of her not giving your authority in your own home is total disengagement from the kid (we won't talk about that today), you staying and being miserable, or you leaving.

It's hard to really give you advice on the others without fully knowing the situation, but in general:

1.) If BD isn't paying CS, SO needs to find out why. Did she not file for him to pay? If not, she needs to. Even an extra $100 a month so one of your SS's two parents can spend a significant amount of time with him would be good. If he just refuses to pay, she needs to keep a record. Hopefully the CSB (Child Support Bureau/Office/Department) is keeping tracking. If they had decided to do CS without the court (i.e. BD just gives her money), but their original agreement isn't covering the basics, she may want to go back and have it re-adjusted based on the state formula (yes, there are formulas in each state for how much CS should be distributed). If BD just doesn't have the money to give, or he is giving the amount he should...

2.) Are there better jobs that your SO could take? Could you all live in cheaper housing? Are there expenses she could cut that would mean she could work less hours? Do you work and contribute to the household (not her share, but your own share)? If you aren't working or contributing, why? Mom or Dad needs to be spending the time raising their son. If Mom is having to support you, well, that's an entirely different talk. If Mom, however, has expensive tastes for herself or her kid, she is going to have to tone them down. If she is barely making it on two jobs, with your income helping pay for some of the household expenses, then it may be time to redo the budget. But now that I have brought up the need for a parent to raise one of the kids...

3.) Could BD have more custody time? If BD doesn't want any more, it's going to be hard to get him to take more. Or if he lives far away, it's going to be hard to get him to take more without just switching custody. If Dad is capable of being a more present figure than Mom is, and Mom can't make herself more available, then it might be time for Dad to step up as the CP (custodial parent) while Mom takes the time to better herself (e.g. go back to school).

How you should approach any of this is based on what the actual issues are. These aren't fun discussions to have, but they ultimately have to happen. Also keep in mind that not everyone is cut out to be a stepparent, and that is perfectly okay. It could be that your SO and BD are doing everything they can and you STILL don't like it. There is nothing wrong is saying "this isn't the lifestyle for me" and walking away. Just make sure that if you want to walk away that you do it BEFORE you have kids with your SO, otherwise you put yourself in your own "broken family" situation.

If you answer some of these questions for us, we can give you some better direction and advice.

This is why I appreciate StepTalk - invaluable feedback and advice from those who have been there, done that. Great post, very valuable questions & sound advice.