Forms :: Search Records And Add Multiple Date / Timestamps

Below are what I have created.

Table 1 with 3 fields:
- UniqueID
- field1
- field2

Form 1
- text box to enter UniqueID
- button to save the new UniqueID and date/time stamp
I set the Default Value for UniqueID in Table 1 as Now()

Each time I enter a new UniqueID and click the button, a new record will be created in Table 1 with the entered UniqueID and current date/time in field1

This form seems to work well.

Form 2
- text box to enter UniqueID
- button to update

How I can use the UniqueID entered into the textbox of Form 2 and update the corresponding field3 with a new current date/time stamp?