Updating a record in sub form from main form

[thrilliam]

I have a main form which is 1 to many subform based on a field customer_ID

each of the two tables has a field called customer_issue

the main form has a combo box which currently fills in customer_issue for the 1 record.
How can I make the event to on update populate the one customer_issue field that it currently does and all of the customer_issue fields in the sub form for the displayed customer_ID?

Thanks,
Will