Statements in parentheses ( ) can be ignored when it comes to Subject-Verb agreement.
Sometimes commas are used in place of parentheses:
His brother, John, lives in Sacramento.
My sister, who works in Miami, is visiting me this week.
Mr. Johnson, however, was not amused.
The teacher, along with her students, is coming to the party.
Prepositional phrases usually have no effect on Subject-Verb agreement.
The men in the car were shouting wildly.
The men in the cars were shouting wildly.
The books on the shelf next to the window are mine.
However, in some quantifying expressions, prepositional phrases do make a difference.
A lot of people are traveling to Belize these days.
A lot of milk was left in the refrigerator last night.
Some of the apples were rotten.
Some of the wine is too old.
None of the water is safe to drink.
Relative clauses can have an effect, depending on the meaning.
Mary is the one who takes care of applications.
Mary is one of the people who take care of applications.
One of the men who live there is deranged.