there is no option to add additional information located on the Add New Listing Package page?

I am not an expert here, nor affiliated with this company, but I was able to do what you are asking. If you are not familiar with child-themes I suggest you learn, as all modifications you make to this theme (and plugins) will be lost when updates to any core files are made by theme / plugins authors.

I wanted to make additional phone and fax fields, which were going to follow the same format and yes/no show field guidelines set in the administrative side of Listing Type settings. For me it was a matter of modifying 4 .php files total.

First, I needed to get those fields to show in the very first step, Listing Type by editing the search-and-go-child > framework > modules > listing > templates > parts > basic-info.php. Since I wanted to duplicate the Show Phone Field Yes/No, I duplicated two times all instances of $show_phone = get_post_meta($post_type_id,'eltd_listing_type_show_phone',true); or $listing_phone = get_post_meta(get_the_ID(),'eltd_listing_phone', true); and made appropriate modifications to my unique meta fields. In my case they were adding a hotline and fax in all instances of either $show_phone... or $listing_phone... 

Using my search-and-go-child, I was able to modify two core eltd-listing plugins files dashboard > dashboard-functions.php and dashboard > templates > listing-type-fields.php. Both of these files take care of the dashboard only. But since the wordpress back-end admin for adding a listing pulls from the same template, then the modified php files will also pull into the back-end side as well. 

The dashboard-functions.php file has two instances of eltd_listing_phone arrays, one for adding and one for editing. Again I duplicated this line twice and and made the necessary adjustments for hotline and fax. The second listing-type-fields.php was again a matter of duplicating the entire section of php code pertaining to adding a phone and replacing the pertinent information.

Lastly, I need to show this newly entered information on listing page itself to my users. Modifying my search-and-go-child folder, I then needed to take care of one more file in framework > modules > listing > templates > parts > item-info.php. Since my hotline and fax are part of the address informational section, again, I duplicated the $show_phone and $listing_phone lines twice to modify with hotline and fax. Then again duplicated the entire php code if ( $show_phone == 'yes' && $listing_phone !== ' ') and made modifications.

If your additions are more complicated, they most likely will require modifications to different php files than I needed. But like I said earlier, I only had two additions that followed an already set standard.

Good Luck,