Related Events is a nice a powerful addon to sell related events to WooCommerce Product page and also Event details page, It will same like WooCommerce Upsell and related products.
Here is way to add related Events to WooCommerce Product page
Here how it will look like in product details page
and Similar way to add related events to event adding area.
and here details page of event after adding related event.
You can buy this addon from this url: Related Events Addon For Event Manager