Yes, In most cases you can keep your existing locks, you can call a locksmith for that type of service. This is referred to as “Keyed Alike”. An easy test to see if your existing locks are able to be keyed alike is to see if the one common key will enter the cylinders (keyway) on the other locks. Generally, if one common key will enter all locks, then they can all be “Keyed Alike”. If your locks are not compatible, you may be able to use most of your locks, and need to purchase few locks to accomplish your goal. Consulting with your locksmith can help get you on the right track, with a minimum amount of money spent.