Ok so you get another container with a dummy load to enable a simple connect disconnect at the loading dock, fine that would work, apart from what you would do when the next load arrives, do you just manufacture dummy loads and take them back to the start, how do these get back to the other side where they are needed, and why don’t we use the same method to move the initial cargo?

If you just have a tank for the water, you could just fill it before unloading.

A few solutions I could think of right off the bat:

• A logistical network so that not every A-B path has to be a net-zero-mass trip, only the nodes - reduces dummy load requirement
• Mass congestion pricing to help balance out the nodes
• Large water bags, send them back empty
• One-way airship travel tourism, brings extra revenue and publicity as a plus

How would you do that in sync with removing cargo, the cargo which probably is a cargo container, and is just disconnected, you can't just suddenly move ten tonnes of water onboard the airship, it takes time to fill up.

A cargo container of water? You're literally throwing your hands up at the smallest issues and pretending you hit mount everest.

Not to mention there's no requirement the weight has to stay the same. Inflating and deflating the balloon controls the buoyancy.

Vacuum the lifting gas out of the giant balloon into some storage tanks to compress it and use some smaller balloons as a tiny giant airship to transport the apparatus back?

As I always say: Physics knows no favours and no bosses.

Boss wants me to do something that physic doesn't allow? I laugh at him for his hybris. No, won't work, because... See first line of this comment.

how hard would it be to have a big anchor that offsets the weight of a couple cargo containers while it fills a ballast with water?