Sibling's great-great-grandchild.
I have 212 great-great-grandniblings (106 great-great-grandnieces and 106 great-great-grandnephews).
Sibling's great-great-grandchild.
great-great-grandnibling.
Half-sibling's great-grandchild.
My half-great-grandnibling is a good person.
I have 128 great-grandniblings (64 great-grandnieces and 64 great-grandnephews).