conflicting axle weights

What happened is the hostler weighed the trailers and it was under 80k, I then weighed the whole set before leaving the terminal and my numbers were lighter then the hostlers numbers.
I then was stopped at the scale in Wisconsin and was under 80k, but my meet driver brought it back to his terminal and weighed it and said it was 84k almost 85k.
I originally said your axle scale may be off a bit. He just told me that he added the axle weight numbers up and that's what he got.

That's why I then asked our terminal mechanic and also a scale repair guy at the truck stop that we meet at and they both told me you CAN add the axle weights up, However its not accurate and that you need a cat scale or 1 piece scale where it weighs the whole assembly.

I just want to make sure this does not happen again, I don't want to send a overweight load down the road to the next guy.