I have now simplified the indexes to
Primary Key: fkn_requisitionid, pkn_requisitionitemid
non unique: fks_stockitemid IDX1
non unique: fkn_pickslipid IDX2
non unique: n_unitsordered IDX5

The Plan is still

PLAN SORT (SORT (JOIN (S NATURAL,I INDEX
(GEN_TABL_REQUISITIONITEM_IDX1,GEN_TABL_REQUISITIONITEM_IDX2,INTEG_297
,GEN_TABL_REQUISITIONITEM_IDX5))))

Also, just ot be clear. I am not particularly looking for help on how
to write sql. Although not as knowledgeable as you guys on the
subject, I have been writing them for years. My main problem is that
Creating an index can cause a 3 second query to freeze indefinitly.
There are literally hundreds of queries so checking and altering any
queries that use the same table is not possible.

Thanks for trying.