Add dropdown selection to list box items

Hello,

Here's what I'm trying to do:

Selecting the item# from a dropdown generates a list of ingredients for that item in another dropdown. The selected ingredient from the "Ingredient" dropdown will then be added to the "Order" list box. The goal is to be able to select ingredients in the order they were used. I'm close, I've got the code pretty much worked out.

Here's my code:

For "Item" drop down custom validation script to "Ingredient" list box-

switch (event.value) {

    case " ":

        this.getField("Ingredient").setItems([" "]);

        break;

    case "Item1":

        this.getField("Ingredient").addItems(["ing1","ing2"]);

        break;

    case "Item2":

        this.getField("Ingredient").addItems(["ing3","ing2"]);

        break;

}

The issue is "ing1" is being automatically selected and transferred to the "Order" list and I want to have to select each one manually.

Thank you in advance for the assistance!