jQuery tablesorter sort only certain rows/columns

I have a table where some rows have a class of "parent" and some have a class of "child". The "child" rows always appear under the "parent" and you can toggle their visibility. What I want to do is use tablesorter to sort only the parent rows based on their "Last Edit Date" column, right now the childrens' "Last Edit Date" column is 开发者_开发技巧getting sorted too and messing up the ordering.

See the answer to a similar question here:

Getting jQuery tablesorter to work with hidden/grouped table rows

The answer provides the following link:

http://www.pengoworks.com/workshop/jquery/tablesorter/tablesorter.htm