tobacco syndrome.

Not direct experience for us, we have barely ever met the Spermidiot's second of 4 all out of wedlock spawn by three different baby mamas.

My SS has never forgiven either the Spermidiot nor BioMom #2 for the birth defects his sister struggles with.

She hates their father too.  Though oddly she does not hold her drunk tobacco engaged mother with the same contempt.  SInce it is her mother that poisened her in the womb.

You have to accept that if you are in a relationship with someone with a disabled child.. that is going to impact your home and relationship.  There will likely be difficult times as a result.  I would also ask you to examine closely your SO to see what kind of person HE is.

It's not totally likely that he wasn't also a heavy drinker at the time.. birds of a feather flock together.. just because he wasn't the one bearing the child.. doesn't mean that he may not have his own issues with addiction /alcohol.  Does he?  

How does he parent? Does  he ensure he has resources for his child?  does he have full custody?  what is their custody arrangement like?  is the EX active in his life?  what is the extent of the child's issues?  are they something you can live with.. and accept that they may limit her ability to move on at 18 as an adult?

She is not going to get better.  She is not going to change. You will be taking care of her for the rest of your life. 
I don't know how bad she is. If she can live alone or not.  Anyone she meets has a relationship with will not be normal  so you have double problem.  You will be funding her life forever   
life this is the life you want to get involved in it's part to you 

My FIL married a woman who has an adult daughter with severe physical disabilities. She has seizures, is wheelchair bound, and cannot communicate. They dated for 8 years before finally getting married. He is fortunate that he does not have to deal with co-parenting as his wife is widowed. 

He said he would do it all over again, but he does admit that it limits his life. It is harder to do everything. Harder to go out on dates with his wife, harder to travel, harder to do daily activities. This "kid" is 24/7. Her health expenses are significant and she will live with them until they are unable to care for her anymore. It is a big commitment and not one to be taken lightly. 

I work in group homes. Fetal alcohol disabilities are typically marked by impulsivity - want, take, have. This also means they can be aggressive, but do not necessarily have to be. They have difficulties with social norms and reasoning.

Do i think it will be harmful to your kids? I don't know. Being around those with disabilities teaches tolerance. I will say every person I have worked with with FAS - did hit others but I am working in inpatient programs. I think it depends on where her skills levels lie & what structures are put in place for her. I would specifically ask about behavior challenges & how they are addressed.

My 22 yr old SS is Autistic and has some other issues tied to that. It isn't the same but I do know what it is like to be with someone and knowing that my SS will likely always live with us. I have to monitor his meds, make sure he using basic hygiene and also deal with a husband who is still active duty and will be deploying for almost 2 years. 

I don't know a lot about FAS but I do know you will have your hands full. Hopefully BM is in jail, and you don't have to deal with her! I will say having a BM like that active in the child's life will make things a million times harder than if she is gone.

Where is the BM in all of this? Does bf have sole custody and BM rights terminated? 

How severe are the childs disabilities from the FAS? How old is bf child?  

Maybe you already posted the childs age and I missed it. 

This is a very big decision for you to make.