Has anyone here replaced their brake lines?

[bxturbo]

I was flushing my brakes on my e53 '05 X5 3.0 and the line going to the rear drivers side wheel was apparently rusted as it started leaking from just behind the driver's door. There's a big plastic panel covering the brake lines so I can't actually see the exact condition until I take it off. There are a few threads on this forum describing the issue but I can't find anything on someone actually fixing this themselves.

I'd like to replace the entire line as opposed to splicing it. But if i can work with an existing union i can do a bubble flare and just replace one section. Does anyone have more info on the schematics of the rear brake lines? I was told I have to drop the rear subframe to gain access to it, but does each rear wheel have its own line? Or is it one main line going to the rear which then splits in 2 to distribute the fluid to each rear wheel? Realoem has a diagram but it's not very clear. Any input from anyone that's dealt with this issue would be very helpful. I'm very disappointed with the quality of the brake lines and expected more from BMW. My '95 e34 doesn't have any issue with rusted brake lines and it's 20 years old.