The thing to ensure here is that the cups are the same size. It just means you do less maths (YES MATHS, not MATH !) and can pretty much ensure the coffee is brewed to the same ratios.
We recommend finding out how much each cup holds, as when cupping coffee we brew the grounds to a ratio of approximately 8.2g coffee to 150ml water.
If you know your cup size, all good. If not use a measuring jug or a bottle/can that has the measurements on it and use that to judge the capacity of your cups.