When adding a new row using the ArrayRow parameter, you need to make sure the number of items in the array matches the number of columns. For example, you can use blank strings for the column that you don’t have the data yet:
{in_EAN, io_FTE, io_PV, io_PAE, io_PCI, "", ""}
Now to update the row later, you need to refer to it by its index. If it is the last row you added, then you can use the last index. So using two assign activities you can do something like:
MyDT(MyDT.Rows.Count - 1)(5) = "new value" ' get the last row, sixth column
MyDT(MyDT.Rows.Count - 1)(6) = "new value" ' get the last row, seventh column
Hope that helps!