Formal:
* Kin: This is a general term for relatives, often used in a formal context.
* Family: This is the most common and straightforward term.
* Blood: This term emphasizes a biological connection, and can be used in a more poetic context.
* Kith and kin: This phrase refers to both close friends and relatives.
Informal:
* Bunch: A casual term for a group of relatives, especially if they are close.
* Pack: This could be used playfully, implying a lively or boisterous group.
* Crew: This term suggests a sense of shared purpose or adventure amongst relatives.
More specific:
* Cousins: A "brood" or "clutch" of cousins.
* Aunts and uncles: A "gather" or "congregation" of aunts and uncles.
* Grandchildren: A "tribe" or "pack" of grandchildren.
Ultimately, the best collective noun for relatives depends on the specific situation and the tone you want to convey.