SSN for dependents. One of them out of the country

Hi:
I would like to know what are my options if my dependents do not have a  SSN. My Son lives with me in Chicago but my daughter lives in Mexico City. She plans to come to visit mid Jun.

My wife also lives in Mexico City (I commute a lot) she doesn't have a SSN either and I don't think she would be interested on having one.
 
What do you think I should do in terms of taxes?

Thank you for your support.

Joaquin