Perhaps it's good to look at the story of this post as an object lesson in "be careful what you ask for." The events of the case didn't take place in Mississippi, but they could and so it may serve as an interesting case study for what can happen when a stepparent who hasn't gone through the process of adoption seeks to exercise parental rights over an ex's children.
The tale of this family started in Serbia in 1998, according to a news report. A woman gave birth to a set of twins there that year. In 2005, she married a man who was not the father and the family moved to Pennsylvania. They separated in 2009 and apparently divorced.
In time, the woman made plans to move to California with her children and it was then that the stepfather launched a legal effort to gain custody rights and prevent the relocation. The basis of his claim was that while he had not legally adopted the children, he had effectively been their father and thus had parental rights.
The trial court in the case granted the man his petitions but denied the mother's counter request for child support. The court said he could not be held liable for support because he wasn't the biological father of the children.
Those decisions were upheld by a mid-level appeals court, but when the case reached the Pennsylvania Supreme Court, it reversed both rulings. The reasoning of the majority of justices was that the stepfather's legal efforts to gain custody were enough to create a parental obligation. And once created, the obligation extended to include a requirement for child support.
Legal decisions from other states don't typically have any direct effect on other states. However, it is possible for courts in Mississippi to use rulings by other states to guide their own. Because of that, individuals seeking remedy through the courts should always work with experienced counsel.