First element of the array is the equivalent of table_id,table_name, room_id and room_name.
If sales is open, first element will be always replaced with the columns data.
if table_id is populated, tables can not be empty.
To empty the tables must be set tables = null or tables = [] and to null also the columns table_id ecc
if there are multiple tables, first element must ALWAYS be father.
Father by api can be changed setting a new table_id ecc but won't be reset the rest of th array by default.
From UI father can only be changed after deleting other tables. Then, father can be changed