Many topics in family law, for both obvious and perhaps less than obvious reasons, garner a bit more "heat than light." As well, family law topics are comparatively under-explored empirically. A recent paper by Douglas NeJamie (Yale) and Courtney Joslin (UC Davis), The Legal Recognition of Multiparent Families: Findings from an Empirical Study, breaks from tradition as it brings data to questions surrounding the legal recognition of multiparent families.
The paper levers two datasets, including all electronically available judicial decisions (through 2022) engaging with multiparent statutes as well as "judicial decisions applying a functional parent doctrine over four decades." When it comes to the judicial decisions themselves, Figure 6 (below) makes clear that judicial activity, while growing, is an emerging trend.