Those two articles are great examples of advanced implementations of a similar idea.
Filemaker 13's "hide object when" calculation should be of great assistance. All you really need to do is calculate a sort order field, the calc would look something like:
if ( recordtype="parent" ; id_pk ; parent_fk & "." & id_pk )
the above would result in the following for your demo:
so the records would sort in the order you have them in. You can use that methodology and adjust to however you need it to sort.
Use the "hide object when" feature to hide your "parent row" fields when a record is a child, and vice versa for a parent record.
in lieu of a static recordtype field, you could use count(childtable::field) > 0 to indicate a parent record.
Wow that sounds like a great solution. Once the records are sorted how do I display the child records indented under their parent record?
I already covered that. Use the hide object feature.