x1 is the step-parent/step-mother/step-father of x2 due to marriage with their parent according to law/custom x3.
x1 does not necessarily raise/rear/parent x2 (for that, rear-concatenate "rirni" as a tertau). The gender of x1 is not specified (nor is the gender of the parent of x2). See also: "pa'uspe", "mamspe", "sperirni", "lacpa".