I have wirelessly extended my network from a airport express base station to include an airport time capsule. I'm wondering can I create a whole new network name and password coming from the time capsule without affecting the network name and password coming from the express
Sorry, but no. When you extend using wireless, the "extenders" always use the same wireless network name and password as the main router. There is no option to change this.
You could do what you ask if the if the devices are connecting together using an Ethernet cable, but the cable would have to remain permanently connected at all times.
Network name and password
