extending length of radiator pipes

[MarcoM]

Hi, I have two vertical radiators, one connected via copper and the other plastic.
I am installing wall insulation so the radiators will have to be moved further by approximately 3cm hence the pipes
will need to be extended. I have posted a pic of the current arrangement. What is the best way to extend these? Should I cut them upstream and install a longer pipe length from that point on or can I add something to the existing pipe end to make it longer?
The diameter is 10mm and goes into a reducer in the valve.
Thanks

 

[blup]

Whichever is more convenient. Leaving them in situ has the advantage they will be concealed, unless you put them under the floor.

 

[ChrisJP]

I don't think you'll find any way just to extend the existing pipe by 3cm. Probably best to cut the existing pipe before the bend and connect it with an inline coupler to a new bent pipe which is the required 3cm longer