Pull Down Box And Locked Text Box On Form

On my first form I have a pull down box and when I select an item and click the add button, the item appears in a locked text box above the pull down box. After I click the submit form button, it goes to another form. On the other form is a similar pull down box and locked text box. So far I got the item selected on the first form to appear in the second form's locked text box.
Again, the second form also has a pull down menu and when I select another item from the pull down box and click the add button on the second form it deletes the first item selected in the first form from the second form's locked text box. The items selected are put in a table. I was wondering if there was some kind of code I can input so the second form's locked text box keeps the first value from the first form and can add additional values when selected through the second form's pull down box. Sorry if this sounds confusing. I really appreciate your help. Thank You.