Onomastics should not *replace* the surnames tag, as there is not a one-to-one correspondence between the two terms.

One can certainly find instances where onomastics and genealogy go hand in hand.  A quick Google Search turned up one such example:

> Dictionary of Americanized French-Canadian Names: Onomastics and
> Genealogy July 2018 *Names: A Journal of Onomastics* 66(3):196-198
> DOI:10.1080/00277738.2018.1500988

Onomastics is the term for the study of proper names, yes, but a proper name can consist of multiple components, as this excerpt from the [[Stanford Encyclopedia of Philosophy][1]][1] shows:

> The Cambridge Grammar of English distinguishes the syntactic category
> of proper name from that of proper noun (Payne & Huddleston 2002:
> 516). A proper noun is a word-level unit of the category noun, while a
> proper name is a type of noun phrase. So, for example, the proper name
> “Alice Walker” consists of two proper nouns: “Alice” and “Walker”. A
> proper name (the noun phrase) may also—and often does—consist of a
> single proper noun, just as a verb phrase may consist of a lone verb.

A surname is a subset of the kind of name one might study for genealogy.  

The volume on all our tags is low, and it may not seem to matter if we choose one term over another. However, what happens in the future if the activity on the site is at a much bigger scale?  

Removing or replacing [tag:surnames] as a tag means that people who are primarily interested in surname studies can't follow questions about surname studies, an important part of Genealogy and Family History.  They won't be able to separate questions about surnames from questions about naming patterns (which might also involve the use of given names) and other questions about name variations. 

What makes [tag:onomastics] a good fit for our site?
----------------------------------------------------

As for the two questions recently tagged [tag:onomastics], and any other name questions that might come up on the site: I would like to see some indication of why the question was posted here and not on Linguistics SE.  

 - [Is the study of proper names really a branch of linguistics?][2]
 - [In Search of an Etymological Name Database][3]
 - [Are there geographic or cultural patterns in surname etymologies?][4]
 - [Linguistics SE questions tagged][5] [tag:onomastics]
 - [Linguistics SE questions tagged][6] [tag:toponomastics]

Compare and contrast with DNA.  Questions about genetic genealogy are a good fit for Genealogy SE. Questions about DNA topics which are not used for genetic genealogy are better suited to the more science-related Stack Exchange sites where they are more likely to be seen by experts who can answer them. 

  [1]: https://plato.stanford.edu/entries/names/
  [2]: https://linguistics.stackexchange.com/q/20304/3675
  [3]: https://linguistics.stackexchange.com/questions/38953/in-search-of-an-etymological-name-database
  [4]: https://linguistics.stackexchange.com/questions/36984/are-there-geographic-or-cultural-patterns-in-surname-etymologies
  [5]: https://linguistics.stackexchange.com/questions/tagged/onomastics
  [6]: https://linguistics.stackexchange.com/questions/tagged/toponomastics