Replacing a radiator in a microbore system

I have a micro bore system and want to replace a single radiator with a double radiator to produce greater heat output in the room. How can this be achieved when the existing input/output valve has a copper pipe running into the inside of the exiting radiator for the flow return? With a standard double radiator the entry for the flow is in the middle of both panels and therefore can not accept a copper return pipe running into it. Any ideas how this replacement can be achieved?
Thanks

Extend one pipe to the other end of the radiator

ChrisR said:

Extend one pipe to the other end of the radiator

Click to expand...

Thanks, I will probably will have to do this but I did not want to drain the system down if possible to fit but it looks like I will now have to do this.