TField MinValue, MaxValue problem

Hi !

I have TFloatField (say, myfileld) with MinValue, MaxValue properties <>  0
It supposed to prevent users from inputting wrong values.
But what I need to do is to allow users to copy existing record ( even with
myfield.value = 0).
I've written some procedure which copying values all the fields from one
records and insert them into new one(except for key fields of course). But
when I try to do MyField.Value := ValueFromSource
I get error message "0 is not a valid value for field Myfield. Allowed range
is ...".

How to solve this ? How to override procedure of checking for
MyField.MinValue, MaxValue ?