Grandchildren's rhymes with:
children's, childrens, childrens', children's, childrens, childrens', polyhedrons, squadrons, aaron's, aarons, aprons, arens, aspirin's, barens, baron's, barons, barrens, barron's, behrens, berens, boren's, byron's, charen's, chevron's, children's, childrens, childrens', chiron's, chyron's, citron's, cochran's, coltrane's, doctrine's, doctrines, environs, farrens, garron's, gearan's, heron's, herons, hirons, hondurans, karan's, karen's, laurens, matrons, mehrens, mulheren's, orens, patrons, polyhedrons, pomrenze, quotron's, rosekrans, salvadorans, sharon's, sirens, sovereigns, sovran's, sovrans, squadrons, terrones, torrens, vestron's, warren's, warrens, zairean's, zaireans