How do I gain ownership of a funeral plot?

Years ago, my mom and step dad purchased 2 burial plots near my grandparents. My mom passed away in 1990 and was put in 1 of the plots. When my step dad passed in 1994, a horrible family feud ensued and he was not buried in the plot he had purchased, but instead was buried in Indiana next to his mother. I want to regain ownership of the plot that sits empty next to my mom. My step dad left no will and has 6 biological children. My feeling is that I somehow need to legally go through these biological children to get what I want. If I don't, this plot will never be occupied because no one else would want it but me. Since it is a parcel of land, how would I go about legally gaining ownership of it?