TL;DR Read ghosts on the network and send them to the logical network. What? Add the additional ability for the drone station to read construction requests in your logistics network. Why? This will allow, based on these requests, to automatically form a train with the necessary materials and send i...

And on trains too.

create a constant combinator with two signals and different values. We create a parameterization and specify one number in both values. Now if you set the plan and specify different numbers, the first number will be ignored and both signals will be assigned the second value. 0eNq9Ul1vgzAM/CuTn9MKGKl...

I managed to make negative values, but this is a workaround. I had to enter 2 additional parameters and multiply by -1 in the formula.

But after construction, the extra parameters hang in the combinator

When constructing a blueprint, you cannot specify a minus sign in the input field.
If you specify a negative number in the parameterization menu, the minus will appear during construction, but the result will be 2147483647.