Assign value from field in main form to field in subform

[larpup]

I have a simple form with a subform. When I enter in a row in the
subform, I need to assign the value of a field [customer] from the
main form into this field in the subform [customer] as well. This is
upon entry only. If the customer is changed in the main form upon
entry I need to update all records in the subform as well.

Can anyone give me an example of code and where to place it? Greatly
appreciated.

Lar