Separate settings for Year / Month / Day / Time (to be used for date of birth or age of contact or group)

I am wanting to have accurate records related to the age of people (and/or groups). At present there is only an age range to guess what the persons age it. The problem is that this range doesn't automatically adjust each year so the info will get out of date.

eg.
I hear that someone had a birthday recently (on a particular date) but if I don't know their birth year I can still enter some info.
I can enter the month date, but leave off the year (or guess it). But this date can now be used to keep the age record in the correct range.

If I don't know the year they were born in but I **did find out their age**, then have a way to calculate what year they were born in.
Or the opposite of the previous...
I want the system to be able calculate their age if **I find out what year they were born in**.

The default age ranges are:

**My solution**
Instead of having one calendar date field, have one for `year`, one for `month`, one for `day` (and one for `time`). That way the info can be used to calculate the age of - whatever you want to calculate.