kissing cousin vs kissing kin

kissing cousin and kissing kin both are nouns.

Word	Noun	Adjective	Verb	Adverb
kissing cousin	Yes	No	No	No
kissing kin	Yes	No	No	No

As nouns, kissing cousin and kissing kin are synonyms defined as:

kissing cousin and kissing kin: a more or less distant relative; familiar enough to be greeted with a kiss

kissing cousin (noun)	kissing kin (noun)
a more or less distant relative; familiar enough to be greeted with a kiss	a more or less distant relative; familiar enough to be greeted with a kiss