Kerry, I stepped through the code and, unless I missed something, it
looks like streamlined does not support this functionality for the
inline editing of the relationship. Its works fine the Edit View
though using the :custom_options_method.
The issue seems to lie in the
Streamlined::Controller::RelationshipMethods module. If you look at
the set_items_and_all_items it just does a @klass.find(:all).
I quickly wrote proof-of-concept plugin the adds an :order_by method
to the Streamlined::Column::Association class and aliased
set_items_and_all_items to use the order_by method. I also modified
the Association.items_for_select method so it also supports the
order_by method. I did that because I would think in cases where the
default query works for you, the only other functionality you would
need is to controller the ordering of the columns.
If anyone is interested I can post it here. I was also thinking of
submitting as a patch because it is really only a few lines of code.