Cabling conundrum

Hopefully I am in the right section this time.......

I am trying to make sense of my adsl/phone wiring in order to find the best solution.

I have 2 separate BT lines into the house, the one downstairs is via an old style single RJ11 socket in the lounge with a phone and Sky box connected, there are 2 further sockets downstairs, both with filters and 1 upstairs in the main bedroom (not used).

Ok so far?

In the main bedroom is an NTE5 socket for line 2 (with filter and phone) and the extension for line 1 (not used), there is a link between the Line 1 extension box and the Line 2 main box. There is a further extension to the back of the house where the PC and ADSL connections are. This extension carries both Line 1 and Line 2.

How? Why? My daughter was going out with a BT engineer

you have the full 8128 / 832 speed, if that is reliable then the only thing to be gained is a reduction in line rental by going to one line ?

Your phone extensions are acting like aerials for noise. Fit a filtered faceplate on the master socket, connect the ADSL modem directly to that, and run a long ethernet cable (if necessary) back to the PC('s).

Ok, the ADSL line from downstairs (Line 1) has an extension box upstairs sited next to the upstairs line main NTE5 box (Line 2). There are 3 cores running from the Line 1 extension into the Line 2 NTE5 box and another cable from the NTE5 box carrying both Line 1 and Line 2 to the back of the house.

If I fit an NTE5 filter plate to the Line 2 box, would this also filter the Line 1 extension running upstairs?