I'd start at the distribution board (if possible) isolated (safely, of course) and with every load unplugged (or FCU switched off).
I'd draw up a list of sockets per room (I usually number them clockwise from the entrance nearest the front door, to save confusion later, e.g. Bed1-1, Office-2, etc.). Plus a plan with these marked on.
At the DB, take one outgoing cable, connect L & N together on that cable only, then with a carefully nulled MFT, measure (R1+Rn) around the ring. Making sure you are getting a good connection to the cable, and not adding anything for a dirty switch or socket contacts. If you've time, open the face plates and measure directly onto the terminals.
With care, you can map out the electrical order of the sockets, generally they will flow sensibly round the floor plan. Note any that are spurs (if you open them up).
I'm avoiding measuring (R1+R2), in case of parallel paths (boiler, hob ignition connections etc).
Repeat for the other cables out of the DB.
Sometimes a couple of sockets are so close together electrically that it is hard to determine which order they are in. But you should be able to get a moderately accurate picture of the cabling, and narrow down the area of cross connection.
Of course the cross connection could be in a junction box under floorboards (is this a domestic property?) rather than at a socket - e.g. a later alteration by someone who didn't understand the wiring properly (or at all).
Edit: If you have a "spider"-type ring where every socket is essentially a spur from a junction box under the floor boards, this method won't be so useful