Marriages between groups of siblings-in-law, which, using kinship conventions, I call ‘GEG marriages’, resemble cross-cousin marriage or prescriptive alliance but lack the repeatability of such alliances in the immediately following generation(s). Although mentioned in passing quite frequently in ethnographic accounts, theory explaining them is largely lacking. Building on previous work, in this note I address the possible reasons for such marriages, both indigenously (and therefore locally) and as a possible waystation on the path to a society abandoning cross-cousin marriage.