Append to an existing LIS structure

Hello,

Is it possible to enhance an existing LIS structure? The LIS is currently being used to store the weekly bucket (planned independent demand) and now the ask is to add one more key field to an existing LIS. Is it possible or shall I go ahead with a completely new structure?

Is it also possible to transfer the data from an existing LIS to a new one if the new one holds one additional field?

Thanks,

Kumarnae