There is a quick tweak that can be implemented in the code, in order to add more than 2 options in the select option:
1) In your theme’s functions.php you’ll have to remove the
‘woocommerce_after_checkout_billing_form’ action associated with the ‘wccs_custom_checkout_field’ function, that is found in the plugin code. You can use the remove_action() WP function for this.
2) You then initialize this action with a modified copy of the ‘wccs_custom_checkout_field’ function as a callback function.
Right where the function code (#836) accepts the input values from Option A and Option B fields for the select box, you replace the input array (‘options’) with an array created using the explode() PHP function (use comma as its separator) and $btn[‘option_a’] as the string input. You then enter more than 2 values using the following notation: Option 1, Option 2, Option 3, etc. right inside the Option A input box. You also have to use a WP sanitize function for the input.
I hope this helps someone…