Hi,
1. In that case, use a single dropdown and in the "custom_fields" file of the view "checkout" via the menu Display>Views, change the code:
echo $this->fieldsClass->display(
$oneExtraField,
$this->$type->$fieldName,
'data['.$type.']['.$fieldName.']',
false,
' '.$onWhat.'="hikashopToggleFields(this.value,\''.$fieldName.'\',\''.$type.'\',0);"'
);
to:
echo str_replace('size="1"','size="3"',$this->fieldsClass->display(
$oneExtraField,
$this->$type->$fieldName,
'data['.$type.']['.$fieldName.']',
false,
' '.$onWhat.'="hikashopToggleFields(this.value,\''.$fieldName.'\',\''.$type.'\',0);"'
));