what i want to achieve, when loading, is to add loaded rows to existing one, not replacing them,
Don't use the setDataVector() method, that replaces all the data in the model. Instead, loop through the Vector that you just created and use the addRow(...) method to add the data to the existing TableModel.
when i have loaded rows from file i can add new rows, but the cell editors aren't working in this case JComboBoxes
Whenever you use methods like setDataVector() the TableColumnModel of the JTable is recreated so you lose your custom renderers and editors. Using the approach from above should also solve this problem.