"the mother of so-and-so." >> "the mother of so-and-so".

American typographical convention puts periods and commas inside quotations; semicolons and colons, outside; exclamation and question marks, inside or outside as they belong or not to the quotation.

This is arguably a bad idea--based not on logic, but on bygone typographers' notions of what looks best--and the argument has notably been made by Donald Knuth. I myself have no qualms about breaking the rule when I think clarity benefits.

As modern practice gives authors more control over the appearance of their work, I should not be surprised to see the convention change. If you've been seeing counterexamples, the change may be underway.

If it happens, I predict it will happen first in the writing of Engineers.

Indeed, in my text clarity and logic will prevail.
Thank you.

There is a technical convention that single quotes are used for terms exactly, so that one writes <The storm is called 'typhoon'.> but not <The storm is called 'typhoon.'>

@nonong

Thanks for the information. It is news to me, but not surprising; and certainly makes perfect sense. Perhaps it will turn out to be the proverbial camel's nose.