Query regarding having middle name in passport but not in other documents


My parents are planning to apply for US visitor visa. My father has middle name in his passport like:
Surname (Last name): MXXXXX
Given Name (First name+Middle name): BXXXXXX NXXXXX

But all his other documents have just First and last name like:
Surname: MXXXXX
Given Name: BXXXXXX

Even mine and my mother’s passport has his name as just (First name+Last name). Will this be an issue while filling up their visa applications? Or is it wise to get it changed in his passport? Or should he use the one without middle name as ‘other names used’ in the application?

Please advice us so that their is no complication regarding the name (just an extra middle name in passport) later in future.

Thank you