Hi Nicolas!
Thanks for reaching out, interesting question – while there isn’t support for something like this included within our ticketing plugin itself, all tickets that you create on Events are technically WooCommerce “Products”. So if you head to the WooCommerce “Products” page in your admin, for example, you should see all your tickets listed there.
What this means is that checkout-related things, or other product-specific features in WooCommerce like the one you’re looking for here, may be possible by getting WooCommerce add-ons.
For example, I have not personally tried this and am not sure if it would do what you need here, but this WooCommerce add-on looks like it would work well for the features you need here → http://docs.woothemes.com/document/chained-products/
I’d recommend looking around at different WooCommerce add-ons, or looking up ways to extend WooCommerce directly – as long as it works on a generic WooCommerce “product”, then it should work fine with any ticket created by our WooTickets add-on.
Does all that make sense? Let us know! And let us know if it helps.
Cheers,
George