An existing tenant at another company will have a paid to date for where they are paid up to, and they might also have a part payment amount - especially if they were with another PM company.
If the owner was managing the property, you might have to get the total amount of rent they have paid since they moved in and work these out.
Assuming they were paid to say 12/2/2012 and had a part payment amount of say $40 towards their next weekly rent of $200, then they must be entered in Palace as follows :
Start Date 13/2/2012 (and therefore paid to date is 12/2/2012)
NOTE - the start date in this case is NOT the original occupation date - it is the day after the Paid to date. You can enter the occupation date in the notes area.
Rent rate : $160 (this is needed the first week to make up the $200, since they have a part payment of $40)
Add a rent change record effective 20/2/2012 for $200 (to set the rent rate for the rest of the tenancy.
If these were not done when the tenant was entered, they can be subsequently be set and the Palace repost will correct the historic transactions.