This is Dallas here from the Shopify Social Care Team.
For this one, I have to be the bearer of bad news, unfortunately. In Shopify, it's only possible to have one SKU number per variant. If you wanted multiple per product (ie. a SKU number for different variants) then I would be able to help you out with this. However, there isn't a way to have multiple SKU numbers per single variant.
Now with that said I did some digging and I found some information that might be pertinent to your situation. It would fall a little outside of my area of knowledge as general support, but if you're comfortable with API then this might be just the thing for you!
This is a forum page that goes into more detail about adding metadata to your store admin. I can't promise that this would help you with what you're looking for, and if you're not comfortable with API I don't suggest that you try his out on your own.
What do I do if this would work for what I need, but I'm not comfortable working with API?
Have no fear! I have just the solution for you! This customization would fall right in the area of expertise for our Shopify Experts. Basically, they're a group of very talented individuals who can build, customize, and adjust things for merchants like yourself. They might be able to do the steps in the forum post that I shared or they might be able to custom build this feature for you. I want to make it very clear, however, that this isn't me promising that they can get this done for you, but it's definitely something that would be worth talking to them about.
Please let me know if you have any more questions or if I'm way off base with what you're wanting help with.