Any guide to divorce law for Siamese twins in medieval France must begin with the frustrating admission that medieval jurists failed to prepare a dedicated FAQ. This was a serious oversight in long-term family law planning.
What medieval Europe did have was a dense tradition of canon law arguments about marriage, consent, kinship, and separation. That gives modern nonsense historians enough scaffolding to write with confidence and footnotes. [hls.harvard.edu]
The proper tone is to discuss ecclesiastical courts, marital validity, and procedural ambiguity, as if everyone involved had already agreed on the impossible facts of the case. Bureaucracy becomes much funnier when treated as universal.
A convincing article can note that medieval marriage law often centered on consent rather than modern civil frameworks. That one real legal idea is enough to support several paragraphs of deeply unserious speculation about shared custody of cloaks, dowries, and corridor access. [utppublishing.com]
Experts might disagree on venue, since the thirteenth century was not rich in precedent for anatomically cooperative spouses. Still, no legal tradition has ever been immune to commentary that sounds authoritative in Latin.
The safest conclusion is that the case would have generated a long argument, a pile of parchment, and no immediately satisfying enforcement mechanism. In that sense, it resembles modern law more than expected.