I wouldn't mind multiple tractors allowing multiple tractor targets. So six tractor beams can move six ships.
Currently, tractor speed is determined by size of the engines of the tug versus the size of thing be tractored by it.
So if a tug had six modules, it'd move slower when towing six 10,000 ton ships versus one 30,000 ton ship. And it would the same speed if it was towing six 10,000 ton ships versus one 60,000 ton ship.
Daisy chaining shouldn't be a thing, really. Although I wouldn't mind some new thing where you can make some sort of "Warp Bubble" that adds speed to the fleet around it. Without adding speed to the ship producing the bubble of course, and capping the speed for ships with a warp bubble to prevent stacking to exploit.