Remember: NEVER use an apostrophe to form a plural of a name. Here are examples of this common ERROR:
The rule: To form a plural, just add ‘s’ or ‘es’:
The Martinezes (Yes, that sounds awkward, but it’s correct. To avoid all those syllables, try revising the construction. Instead of this:
I know all the Martinezes.
I know the whole Martinez family.)
When you need to make the name possessive, the apostrophe is correct:
The Singhs’ house
The Joneses’ party
The Martinezes’ wedding
Note that you form the plural first and then make it possessive.
For a single person, just add apostrophe-s:
Rav Singh’s house
Karen Jones’s party
Julio Martinez’s wedding