Hi Marlongarz,
Yes you can include him on your PR app as long as you have the proofs, that you've stated, of your common-law relationship.
BUT problem may arise on your living out situation with your employer.
I am certain that you know that the program requires you that you must stay and live with your employer while employed as a live-in caregiver.
In order to be granted a Permanent Resident Status, this setting is a must and is one of the questions stated here:
http://www.cic.gc.ca/english/information/applications/guides/5290E2.asp I recommend that you convey your thoughts with your present condition.
