fixing multiple variations and combining into one

i’m working on a site where the original designer made product specific variations for clothing. Example:

variations:
blue-jeans-1-waist: 30,32,34,36,38
blue-jeans-2-waist: 34,36,37,38,40

but this is horrible for searching and everything where i’d like to show only jeans where the waist is XX.

for the above variations, i’d like to create a single variation called “jeans-waist” and have 30,32,34,36,37,38,40

and then apply them to the 5 products that are already created with a mix of variations.

is this as simple as it sounds, or will i have to create all new products? can i just apply the new variations to the products, and since the values already match, it’ll just work correctly?