Multiple filters

Gday all,
Not sure if this is in the right spot, but would love some help. Not sure if it's possible, but I would love to filter my spreadsheet in the following way.
I have 7 columns, but I want to sort by 3 of those in a particular order.
The 3 columns are Due Date, Completion Date and Completed (as a %)
Ideally i would like to have stuff that isn't 100% sorted by due date. Once 100% complete ordered by completion date. But I would also like completed tasks to go below incomplete.
I know this sounds tricky, but I think i could do it with a combination of filtering and Conditional formatting perhaps?

You could do this by adding an extra column to check if items are complete. If the % complete is in G2 put =G2=1 in H2 and copy it down. This will give a list of TRUE and FALSE. You can sort by this new column , then by Completion Date, then Due Date.