I don’t think there’s an easy shortcut… it’s probably 6 of one, 1/2 dozen of another.
You could create 1 measurement file with custom right and left measurements, then draft a left and right side… OR you could create 2 measurement files - for left and right, draft just 1 side. Load the left measurements, create a layout & print that side, then load the right side measurements and repeat. Either way you’ll end up having to print 2 sides.
Personally, I would make one measurement file with extra custom measurements for the side that is asymmetrical and draft the 2 halves along side each other so that I could check the flow of the pattern (that the 2 side do match in all the right places, will fit in the right places, etc.).
Another way would be to draft for one side, print the pattern twice and then do the changes manually on the one half
Although it will take quite a bit of time, if you have the measurement file nicely set up and you create a basic pattern from them that fits, it will work for you for a very long time and you will be able to use it for many other designs later.
I’m drafting bras, which means I have to use different measurements for each breast. I always create two fields in seamly me, each for one side. Then I can be sure the correct measurement is used
Plus - you can draft in same file
Sorry I’m so late, Congratulations because you have beaten the disease, thank God. During my life as a Designer, I have designed garments for some ladies with the same problem. And after trying several methods, the one that has given me the best result is the following:
1- Design a bra pattern according to your measurements before your illness.
2- add a lining to the side you need, like a bag, fill it with some spongy material, for example wata, in such a way that you feel comfortable.
3 - Wearing your new and fixed bra, your bust measurement is now symmetrical and you can make your desired patterns and styles with Seamly2D.
You will need to actually draft the 2nd half to use different measurements. By mirroring, you can edit the measurements in the 1st half and it will automatically change the 2nd half because they are linked, an exact copy, reversed, which can be really handy when creating patterns for a cutter or projector.