Extending a hierarchy / Mapping a field in the script onto another field

[#1]

I have a table loaded as follows:

LOAD NodeFullName,
node_name,
grdOrgId,
hier_id,
[Book Name] AS book_id,
[Node Leve1 1],
[Node Leve1 2],
[Node Leve1 3],
[Node Leve1 4],
[Node Leve1 5],
Depth,
Instrument
FROM
[Hierarchy.QVD]
(qvd);

I now want to extend this hierarchy by mapping the value for the field Instrument onto [Node Level X], where X=Depth+1.
Note that we only have data for Node Levels 1-4, so no extra Node Levels need to be created.

Any suggestions are welcome!