grandfamily
n.— «Enrolling a child in school, getting a child vaccinated or adding a child as a tenant in an apartment complex can be extremely difficult and sometimes even impossible for a new “grandfamily,” a term coined by several grandparent support groups.» —“Grandparents find little help raising grandchildren” by Wendy Dahle The Herald (Bradenton, Florida) Oct. 1, 2005. (source: Double-Tongued Dictionary)