At a minimum......Get some chains or cable, 2 per car, about 4-5m long and jack the cars up carefully, and used the chains/cables and come-alongs to connect the lower front area to the lower rear area. The floors and subframe area completely rusted through and the floors have collapsed; that is obvious from the way the cars are sitting. If you just pull on either end, you're likely going to mess up the roofs and tear them apart at the A-pillars, and perhaps bust the glass.
If it were me, I'd jack them up in place, it enough was left, remove the interiors, and take along some steel tubing, a generator, and a MIG welder, and tie whats left of the front and rear together before trying to move them. I'll bet the floors and rockers are almost totally gone.