1) If no Window Label is defined in the widget, the label value comes from the first row of the screen. That will include the display values of any fields that are on line 1.

2) If there is a Window Label defined in the Window widget, that is used instead of the line1 text. You can name the widget and use ILF in Pre-Display of the image that contains the Window Widget definition. Read the widget by name, change the label, and rewrite it.

If you have an INPUT process with a Window widget Label and call another INPUT process that is the same or smaller size but has no Window widget and has Box? = No, the screen contents will be layered into the prior window and the prior windows widget will still be enforced. You can break this reuse by setting Box? = "?" on the child process frame, and/or add a Window widget to the child image.