passing date and time to reply form

[Fred]

Hello,

I created a custom form utilizing the message form with
separate compose and read pages.

I added a Text box to the form with the "type" set
to 'date/time' and "property" set to 'value'. I set the
initial value of the field to 'NOW()'

In the actions menu I have setup the 'reply' action to use
the same custom form and include the original message text
when responding.

Is there a way to code the form to ignore setting the
initial value of this field when performing a reply?
I don't want to lose the date and time that was captured
in the original message.

Thanks in advance,

Fred