Advice????

Mommyof2&2

I thought this would be a good place to ask for some advice. My sister is has some difficult decisions to make in the coming months and I thought maybe you all could give us some input.

 My sister has 3 children 7,6, and 4. She's now pregnant and due in May 2012. Her ex-husband was a dead beat to put it nicely. Her youngest 2 barely knew their father, but the oldest remembered him most. She moved to Indiana from Florida right before the last one was born. This man was a horrible person. He went to jail a year or so ago for robbery at gun point. Later my sister found out that he had been claiming social security benefits for himself and their children. Three years ago he claimed a Jane doe body as my sister that was in a morgue, got a death certificate, and claimed all the benefits including food stamps and medicaid. The scariest part is that he had this woman cremated and who ever her real family is will never see her again. We're not even sure that he didn't pump her full of drugs to kill her. The only reason my sister found all of this out is because she applied for school loans and the turned her down because she was legally DEAD. After the FBI got involved he was arrested. A few days later he overdosed and died. We aren't sure how it even happened or why he was even out of jail. So as bad as it sounds that was almost a blessing. This man was toxic. Her oldest child was really the only one emotionally affected, although they all cried. She is the only one that actually felt any connection to him. They haven't had a male figure in their lives at all other than him. My sister lives with my Dad and step-mom and has never brought another man around her kids.

Well she found out about her ex and then 2 days later she found out she was pregnant, from a man she decided to "be just friends" with. She has no plans of marrying this guy. This man has 4 children from 3 other women. I think he has custody of a few of them. So really it's a strange situation. My sister has never really been good at showing her emotions, but she just thinks every thing is going to be ok. She never has to worry about her ex taking the other 3 for visits or vacations. This child she can't just do what ever she wants with. They picked out a girl and boy name that she wasn't thrilled with but she went along with it. She went and had an ultrasound done at 14 weeks to find out the sex, which probably isn't even right so early. It wasn't for me at least. At 14 wks my youngest girl was proclaimed a boy... only to find at 20 wks she was a girl. She is giving the baby his last name, which I don't think is right. Not only will it be different than her other 3 children and herself, but I would feel like it's adding my child to a growing list of children with his last name. She dated this guy for a few months at the beginning of the year, then they split. They had sex one last time to test out the waters again and decided to be friends. She hasn't thought about child support or custody or the fact that she is just doing whatever he wants her to do. I feel bad for he other children because this is so confusing. My sister never really has listened to any one. I mean it took years and 3 kids for her to see that her husband was a bad person. I feel bad for her, like she isn't seeing how hard this is going to be. Even though she was already a "single parent" before, her ex never even spoke to her children. I just don't know what to do to help her see that she needs to get into gear. She needs to make a plan. I had to go online and fill out her paperwork for medicaid because she just never got around to it. My other sister and I don't even think she is really seeing a doctor yet. I feel like I should be giving her some guidance. 

Should I talk to her about my concerns? Should I just leave it alone? Would you help her see this isn't all roses?