SMMware keeps a history of addresses for a client. The approach used parallels the reality of when addresses change.
After the original address, future addresses are associates with jobs. There are different kinds of jobs (Examples: Move only, Downsize only, Move & Downsize, Handyman Services), but only a couple of them involve moving.
If the job involves moving, the fields for the "Move To" address will appear.
When you first create a client (and before you have a "move type" job), the Edit Client screen lets you enter the client's "original" address.