How to add custom month in Date field? In my academic website, I need to add graduation year as a date field but for month field, I want to add only two month (May and December).

Can I do this?

My professor want like this and i don't have any idea to solve my situation.

Can you help me?
Use hook_form_alter to change the date field on the node form you can only select those two months (and disable the rest).