co-grandmothers

Noun

co-grandmother (plural co-grandmothers)

1. the mother of one's son- or daughter-in-law, as common grandmother of their children; the relationship between women who have grandchildren in common; maternal grandmother vis-à-vis paternal grandmother.
   • Talk to enough grandparents and one thing becomes clear: Because she's closer to the mother of the children, the maternal grandmother generally has a slight advantage. Or, as Audrey Berson […] put it: "She's my daughter, so I have the edge." Even so, Berson's co-grandmother works in the same town...2009 May 19, Beth Teitell, “Horns Come Out When Grandparents Envy Each Other”, in Boston Globe, archived from the original on 03 Jun 2009, page B7

   Synonyms:

   co-mother-in-law