How to route a site

Our site must be connected with the Englisch beeline.co site. It’s our mother company. We will be using nl.beeline.co.
Is this possible and how can we do this?

Customers from holland arriving via the UK site will get the change to go to the dutch site.
Crucial is that we can run the site independent of the UK, but we share the beeline.co domain. Can you let me know what we have to do and what UK has to do to get this up and running