COLLATERAL – relatives descended from the same ancestors, but in a different line (aunts, uncles, cousins – those not in your direct line)
Merriam-Webster Online Dictionary
collateral (adjective)1.
a) accompanying as secondary or subordinate - concomitant digress into collateral matters
b) - indirect
c) serving to support or reinforce - ancillary
2.
belonging to the same ancestral stock but not in a direct line of descent - compare lineal 3a
3.
parallel, coordinate, or corresponding in position, order, time, or significance - collateral states like Athens and Sparta
4.
a) of, relating to, or being collateral used as security (as for payment of a debt or performance of a contract)
b) secured by collateral
1.
a collateral relative
2.
property (as securities) pledged by a borrower to protect the interests of the lender
3.
a branch of a bodily part (as a vein)