I think my dilemma with this is that the kids will suffer

If the kids suffer, that is on your partner. He is the one who should be helping with homework and doing for them, anyway.

I was semi-disengaged because I have never wanted kids. My husband has always been very hands on and nurturing and had no problem taking care of his daughter, all on his own (including cooking and laundry). But, he did not dismiss me in my own home. I made rules and my SD had to follow them, like no food or drink in the living room, cleaning her room, etc.

Do you think your partner doesn't feel like you have a say because he doesn't really consider it your home, since he owns it? Do you help pay the bills? Do you have a say in things not related to his kids? Because that would be a whole different issue, to me.

There are many different levels of disengagement and different reasons for it. You don't have to jump into it all at once, either.

I disengaged, cause I was expected to do everything for skid, but I was not allowed to discipline or give any instructions to skid... small things like .. could you please take your dishes to the washing room...

Thus I decided to disengage, 100%... I do nothing for skid I simply say ASK YOUR DAD...

I do not care if she suffers or not, she made it clear I'm not her parent I can not tell her what to do, thus she made it clear, I'm not her parent I don't have to help her... it's that easy, yes she did suffer, cause I was the one buying her things, toiletries, nice fashionable clothing, drove her around and her friends... then I stopped.. the day she told me I'm not her mother...

read the link on disengagement
http://www.steptogether.org/disengaging.html

So what would happen if you sat down this one young pre-teen and one young man and simply said 'I've been doing all the physical chores and needs for quite a while and with two able bodied children and another able bodied adult in the home, it's time some things change'? Show them what you expect as far as picking up after themselves, how to do their own laundry, taking part of being a member of the household by cleaning (mopping, scrubbing, garbage whatever).

Going on to say how , now that they are getting older it's simply time you're able to make time for things you enjoy instead of spending so much time doing the things they are now quite capable of doing/helping with. You can still attend the activities of the kids you choose but you want to be able to join an adult activity you also enjoy.

I think so many ladies fall into a early pattern of either thinking they must prove themselves Wonder Woman and/or really believe all this household stuff is actually all stuff the woman of the house is suppose to do. Once they realize how unfair it all is and that she's somehow turned into the house servant/maid resentment and hard feelings develop.

It's ok to say 'no more'. It's ok not to feel a darn bit guilty over it. It's not the kids it sounds like you need/want to disengage from , but rather being the sole person the house depends on to keep it running. These young males are going to grow up thinking the hard and non-fun work is all stuff for their own future wives to do. Who will want to marry a non-team player? What if they remain single for years getting their education and sowing their oats? Who will do it all then and take care of their every last need and comfort (feeding bellies, cleaning their bachelor pads, making sure they look human and not homeless when they get to work).

I don't 'get' why either of the two males parents would object to their children not becoming needy slobs and don't know how to lift a finger. Perhaps you don't need to disengage from kids as much as you just need to go on strike and get these three able bodied males in your home motivated.

Sd doesn’t talk to me, which to me is disrespectful, but not to dh.  So I don’t go out of my way to make conversation with her. If either one of them ask me to do something for them, including fixing a meal, I expect a please and thank you, and no smack.

Don’t ever, ever, ever let anyone mistreat you because they have given you gifts (in this case free housing).  That shouldn’t even play into the reason you disengage.  You don’t owe your dh anything.  If he thinks you owe him something, and holds it over your head, that is abuse.

My greatest finds were the disengagement essay, and bible.org has a great free read on boundaries, which can apply to anyone (and if you’re not Christian just leave out the God parts).

I feel this so intensely. I am in a similar situation with a man I adore...but his kids have no responsibilities or hygienic habits. As a GF I am more invested than I should be, but I am also growing resentful that I do so much and Dad won't establish some rules / responsibilities and enforce them. Me trying to parent just makes me the evil step mom. 

Where can I learn more about disengagement? I have also had conversations with the BF till I am blue in the face and he doesn't hear me. I also fear the kids will think I don't care anymore. 

Sorry you are experiencing this. I do very much understand this struggle. 

I don't think there is a problem and your Sks shouldn't have a problem with your decision either. You can simply make the decision that they are both old enough and independent enough at thier ages to wash thier own clothes, make simple meals and clean up after themselves.  The oldest can get a job and start paying for some of his own things and you dont have to be his mode of transportation. If he doesnt have a car or license, public transportation is just fine. It has nothing to do with them being SKs those are the same standards I put on my own child.  I tell him daily I am not his maid.