I'm not a Now TV broadband user nor do I have a Now TV hub, which I believe only has two Ethernet ports instead of the usual four.
That said, the solution that follows is something I picked up from another forum member some time ago and I cannot, for the life of me, know where in the forum to find it.
Here we go:
This device, once plugged into one of your existing hub ports, will give you an additional four ports that you can use. It's similar to a four socket electric extension cable, i.e. plug it into your main socket and get four usable electrical sockets.
I would suggest before purchase that you do some research into this device so that you are certain it meets your requirements, especially that it comes with or you buy the necessary cables to ensure it works.
Hope the helps.
PS. This devices is available from Amazon.co.uk
PPS: It is possible to use another router to receive Now TV services, I know because I do, but if you go down that road you will not get broadband support from Now TV.