WP Manager & Sell Tickets – Cart Issue

I am writing on behalf of my client who has integrated wp-manager free version and sell ticket feature on to their website.

This is the link that we are using

https://ceylonliteraryfestival.com/events-directory/

The issue we have is when a user add an event ticket to the cart, and go back select another event and add that particular event ticket, previously added one gets removed from the cart. We want the ability to add tickets on multiple events at the same time if a user needs so that it will be easier for them to checkout. Most of the customers are complaining that it is very inconvenient to them.

Also, for attendee forms, if the attendee is the one person who will be coming to the event sessions, there should be option to fill same details in one click for eg like in woocommerce checkout area there is a checkbox to enable/disable for shipping address.

let me know how we can do this either from a template or a snippet that can be added to the function.php of the theme