I-130 question on petitioning for my father and step mother

[tciinc]

hello all. Here is my current situation. I'm 30 years old USA citizen and my natural father and my step mother (they got married after my 18th b-day) live abroad.

I can petition for my father without any problems. But I can not petition for my step mother since they got married after my 18th b-day.

So the questions I have are:

1) if I apply for my step mother regardless and receive a denial would that have negative impact on any future petitions on her behalf?

2) Since even petitioning separately I still have to indicate the relation between the 2 applications (the one for my natural father and another one for my step mother) would the ineligibility of the application of my step mother affect in some way the good standing status of my father's application?

4) How would they reunite. My father is 60 years old and he needs his spouse.. any help is appreciated.

Thank you for your advise.
Tciinc