Can I swap the tumblers between two different locks from the same manufacturer? 
In this particular case, is it possible to swap the set of tumblers from one of the knobs into the wave handle?
The deadbolt on my front door is difficult to get the key into and out of and I've currently got no key to my back door at all. So I'd like to just replace both sets and get everything operating on one key that works everywhere.
The only catch is that I've got a lever on the front door instead of a knob, and I actually really like that as it's much easier to operate when you have groceries or the like. So, I'm planning to buy a full double-set of keyed alike knobs and deadbolts for the front and back door and a lever for the front foor. Then just swap out one of the sets of tumblers from the full set into the lever if possible. I'd hope it would be, but I'm uncertain.
Best Answer
I generally go to a locksmith for that kind of thing. Locksmiths come in 3 flavors.
Use the third kind. They're the hardest to find, natch.
That said, the big-box stores do have a possible option for you. One lock manufacturer (don't recall, except they actually do have a reasonably well-reputed history in the lock business) has a mid-consumer-tier product where you can re-key the tumbler yourself. It's pretty slick.
You stick the old key in. You stick a special slotted tool in a tiny slot. This allows you to turn the old key in a weird, awkward, backward way. You pull that key out, put in your new key, and then do some other twist with it. Voilà - your lock is now keyed to the new key.
We're not a shopping site so it isn't really for me to say the brand, but you shouldn't have any trouble finding it.
One more thing about buying consumer tier locks at the big-box store. Look at the package. That package came in a cardboard box which holds 4-12 packages. Flip the package over. You'll see there's a "Key Code" displayed somewhere on the package. Every package in that box has the same Key Code - go look! That's handy if you want more than one package's worth of locks keyed alike - in fact, that's why they do it.
However, it also means anyone else who buys that lock, that store, that time, has a key to your house. Ewww. For this reason, when I buy locksets, I buy them at a store far, far away from my usual paths.