One's sibling or kin via a godfamily tie: one's or one's child's godparent, or one's godchild's parent, or one's godparent's child.
One who tattles (reports others' wrongdoings), often a child seeking attention.
One who gossips, often for the sake of attention.
telltale; giveaway
To act as a tattletale; to tell on; to give away, reveal, or expose.