Okay, children, in today’s lesson we’ll talk about plural names. In general: no apostrophes. Ever.
I am a Dennie. Pam and I are the Dennies. We are not the Dennie’s.
If your last name is Jones (already ending in an “s”), you are the Joneses, not the Jones’ or Jones’s. An “es” may also be required to pluralize names ending in z, x, ch, and sh (the Alvarezes, Marxes, and Nashes, for example).
If a name ends in “y,” such as Kennedy, don’t you dare pluralize it as “Kennedies.” As a proper noun, just add an “s” and make it Kennedys. Again: NOT Kennedy’s. More than one blackberry may be blackberries, but if you own more than one Blackberry phone, they are Blackberrys (and not Blackberry’s).
I know it takes a great deal of restraint to NOT pluralize with an apostrophe, but it’s the right thing to do.
Class dismissed.