AcDbTable::insertColumnsAndInherit

Acad::ErrorStatus insertColumnsAndInherit(
    int col, 
    int nInheritFrom, 
    int nNumCols
);

This function inserts the specified number of new columns into the table at the column index col.

Returns Acad::eOk if successful. Otherwise, returns Acad::eInvalidInput.

Parameters	Description
col	Input integer specifying the zero-based column index for the cell
width	Input width for the inserted columns
nCols	Input number of columns to insert