Invitation Letter for Parents and In-Laws


I would be graduating this semester and would like to invite my parents and in-laws for my commencement ceremony. I had a question regarding the invitation letter given by the college to mail to my parents and in-laws.

Now, I am planning to take 2 different dates for visa interviews for my parents and in-laws. In this case, do I need their names on two separate invitation letters or only on one single invitation letter?

Some help regarding this query would be highly appreciated.

One single invitation letter, one date for all 4 of them would be best. It reduces need for parallel evidence. An invite letter from College is great. If you are also writing one, address it to US Consulate, Visa Section, City, State, Country informing the consulate that you are inviting family for commencement and they will be bearing their own expenses, health insurance and also describe a brief itinerary.