How Do I Retain Previous Data In Numbers for Mac?

Our company sublets rooms to clients. Sometimes clients move to different rooms in the same property. Other times clients relocate to another property. We have a Tenant Master Roster with info like name, current room, and current rental rate. We also have a Property Master Roster with the costs of the various rooms at the property. We also have a Rent Master Roster that shows rent on a per client, per month basis. What we now need, I’ll explain with an example:
In the Tenant Roster, we have Jane who started with us in January and we’ve assigned her to Property #1001 in a $600/mo room. Then, in May we reassign her to Property #3624 in a $700/mo room. Our Rent Roster needs to show she was at #1001 @ $600 from January until April, then from May on the Rent Roster reflects the new assignment location with the new rent without destroying data from the first assignment.
I hope I’m making that clear. Thanks for your help!
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Joey Kango