Birthday in backend without year?

Hello SI-Support,

we would like to add birthday to show in new birthday module. Now we want to add in backend each users birthday, but don't want to use the year because of private policies. Now, if i am adding a birthday without year, it does not save the day and month neither. If i am editing a user with complete birthday an want to reset the year to nothing, then on saving, it uses recent year again.

I dont know how to use the data protection settings for birthday field and how to not add year of birth…? Ist there a way or ho to use data protection otherwise?

Thank you and best regards

PS: We are on a privat intranet, that is why you can't take look at the page, just the screen shot form my backend.