If I would connect some helium balloons with metall wires to my drone would this reduce the take-off weight legally?

Hello there SanDroneMedia. Good day and thank you for the inquiry. DJI do not recommended this process. Metal wires can give out signal interference that can affect your DJI Drones performance when inflight and may caused unwanted incident and it can also void the warranty of your DJI Drone. Thank you.

Ten out of ten for imagination, but don't try this at home