Changeover Contract for Partial RO

Hi Gurus,

How do we treat contract and rental object for tenant changeover in partial RO ?

Assume we have two years contract with tenant A for RO X 1000 m2. RERAPP full amount have been done at first month. RERAALCN also has run in every month. After several months, there is changeover tenant A to tenant B for only 400 m2 of RO X and for the rest (600 m2) is still rented by tenant A.

With tenant B we do not bill rental charges anymore because tenant A has paid us 2 years rental charges for total spaces.

Please, I need your input, is there any best practices to handle this case?

Thank you,

Budi