Using prefixes bis-, tris-, etc.

[K Honeychurch 1K]

I know that you use these prefixes if the ligand has a name with di-, tri-, etc. but in 16.29 (d) sodium bisoxalato(diaqua)ferrate (III) and 16.30 (d) sodium tris(oxalato)rhodium(III) the book uses bis- and tris- in front of oxalato. Why?
Also, why are diaqua (in 16.29d) and oxalato (16.30d) in parenthesis?
Thanks!

[Chem_Mod]

Multiple polydentate ligands in a complex are named using the bis, tris, tetrakis convention. Parentheses around ligands help to emphasize that they are separate ligands independently binding to the transition metal ion and not part of a larger binding to only one site.

[Chem_Mod]

If the ligand already contains a Greek prefix (e.g. ethylenediamine) or if it is polydentate ligands (i.e. can attach at more than one binding site) the prefixes bis-, tris-, tetrakis-, pentakis-, are used instead.

[Jeannie Huang 3B]

Why does that problem put diaqua before bixoxalato? Isn't it supposed to be according to alphabetical order?
so sodium diaqua bisoxalato ferrate (III)