How to calculate the replacement current of two or more currents, so that the resulting magnetic field is as close to the original as possible?

My senario where I want to apply this is quite simple, but I am sure this is relevant in many other settings, too. I have two conductors in a fixed, parallel setting (in my picture they come out of the plane). Now I want to simplify the setup by replacing them with a replacement current, so that the resulting magnetic field is as close as possible (in the far field) to the original. How do I go about this? Some corner cases seem obvious:

If the currents are the same, with differnt signs, the replacement current is their sum (zero) and they cancle each other out.

If the currents are the same, with same signs, the replacement current is their sum (double) and the replacement current would be in the middle, between the original positions.

This seems very basic. Is there scientific consensus how to do this? Is this school book knowledge? Is there a quoteable source for this?