There are lots of options on your dates - however, all of them will involve flying Air Canada - which means $800+ in fees PER TICKET in fees.
If you are looking to pay about $200 in fees, you will need to double connect via ORD and FRA on UA and SK (available on 17th for 5 seats)
You may also wanna look at flying LOT (if available) - fees are much lower than AC/LH/OS.