Ok,
I understand…
You should be able, while in your DG1 interation copy a static path from your EVN date field to the iterated variable of the DG1 date field you are trying to populate.
Then the same date would only get copied when the iteration occurs
within the segment iteratate for the DG1
copy
0(0).EVN.00100.[0] to 0(0).DG1(%s1).00379.[0]
This should do what I believe you are asking.
Make sure you verify the field values I have selected in addition to the variant paths that I have selected.
This will place the EVN date/time stamp into every DG1 Diagnosis date time.
Is this what you are looking for?
Ryan