Birthdate format problem

In Join form, required birth date format is Day/Month/Year . Some people fill it in wrong format like 10/24/1980 mostly out of mm/dd/yyyy habit. For such users birthdates are showing 0/0/0000. Signup form does not stop them from filling wrong data i.e. month greater than 12.

Is there any Check I can add thru Field Builder for the DateOfBirth field that will stop them from signing up with wrong format?

There is a php check field in the fields builder for dateobirth but I don't
know the code to test for the format.

Perhaps someone that does will come forth  .....

Has anyone figured this out yet? I am having the same problem and it is getting frustrating. An acutal fix would be great, but a field validation script would do. Any one know if this is in the roadmap to be fixed?