Copy value from subform1 to subform two when all are open

There are two continuous subforms in main form. All are linked with
ticketNum. When user comes to subform2. I need that Field3 of subform2
will automatically filled with field2 (field2 is a textbox) of
subform1. Field3 is a listbox where i need that user has to select
single or multiple values. control which i am using is a listbox in
field3. How to i do that needs help.

Thanks.

.

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