How to create a function that 3 or 4 of my method can call the function

Carefully read the solutions we provide.

First step:
Rename edtYearKeyPress event handler to EditKeyPress
Did you do this ???
How -> Click on a Edit component, Press F11, retype the name of Event in the OnClick section to EditKeyPress,
Press enter

No click on a other component. Press F11, go the onclick event.
There you should find the EditKeyPress event.
If you don't, then either the components are different, like a TEdit, TComboEdit, TcxEdit, ... and have different OnClick event handlers

Do this for all the components you want to be handled.

If you want the event handler to act differently based on the component or kind of input you want ...
Example.
I have 7 edit components
I want the user to be able to enter in the some only digits, one only capital letters, in 2 of the edits lower case,
in others the user can enter what he wants
This means i have 3 different types of input:
0: Anything
1: Digit
2: UpperCase
3: LowerCase

The way i would do this is to use the Tag property and set it to the type of input i want:
My event handler would then be :



procedure TfrmAdmin.EditKeyPress(Sender: TObject; var Key: Char);
var Ok: Boolean;
begin
  Ok := True;
  case TComponent(Sender).Tag of
    0: ;                                                               // Do nothing all input ok
    1: if not (Key in ['0'..'9']) then Ok := False;  // Only digits
    2: if not (Key in ['A'..'Z']) then Ok := False;  // Only uppercase
    3: if not (Key in ['a'..'z']) then Ok := False;  // Only lowercase
  else
    begin
      ShowMessage('Event handler not supplied !');
      Ok := False;
    end;
  end;
  if not Ok then Key := #0;
end;