Drop down box dilemma

Good day,

I have a drop down list in a row and a button which copies whatever is entered in the row to another table.  The name selected is copied into a floating field in a text box.   My issue is that one name in the drop down should not copy to another table if it's chosen.  Example:  The row "Type" has "Cat, Dog, Fish".  If Cat or Dog is chosen in the "Type" row and you click a button to copy whatever is in "type" to the next table then "cat or dog" is copied to another table in it's floating field. But if "Fish" is chosen in the "Type" row and you click the button then "Fish" should not be copied.  Is there a script for this?  The reason why "fish" is not copied is because "fish" has a sub category list, indicating different types of fish to choose from.  When fish is chosen, the sub list appears.  When you choose "goldfish", that name if populated in the other table.