great-grandnephews
Siblings' distant offspring
Great-grandnephews is the plural of great-grandnephew—the great-grandson of one's sibling.
Put another way, a great-grandnephew is the grandson of one's nephew or niece: My great-grandnephews are starting college next year.
Those who come after
- heirsThose who inherit
- offspringBiological descendants produced
- progenyOne's biological descendants
- posterityFuture generations collectively
bloodline · genealogy · ancestry · heritage · pedigree · succession · dynasty · forebears
Siblings' female children
- grandniecesFemale relatives two generations removed
- cousinsRelatives through shared grandparents
- relativesThose connected by blood
- kinBlood-connected people
Relating to age groups
- eldersSenior community members
- youngersThose less aged
- legacyWhat's passed down
- continuityUninterrupted progression or coherence
inheritance · succession · primogeniture · birthright · patrimony · heirship
descendants
Those who come after
posterity · bloodline · genealogy · ancestry · heritage · pedigree · succession · dynasty · forebears · scions
nieces
Siblings' female children
- grandniecesFemale relatives two generations removed
- cousinsRelatives through shared grandparents
- relativesThose connected by blood
generational
Relating to age groups
continuity · inheritance · succession · primogeniture · birthright · patrimony · heirship
great-grandnephewsgreat-granduncles
Grandparent's uncles
great-grandaunts · great-great-grandparents · ancestors · forebears
great-grandnephewsgreat-grandsons
Grandchildren's sons
great-great-grandsons · great-granddaughters · great-grandchildren · direct descendants
great, grand, nephew, grandnephew, great-grandnephew, nephews, grandnephews, greater, greatest