Full Timing Married Couple in the Back Yard

That is all nice, @ButchandBri, but it is still important that you check with the authorities. All that is required to make this arrangement really stink is hours in court trying to get out of hefty fines because the zoning laws in your county don't allow it and a neighbor who doesn't like you complained.

Assuming that there is no problem there, it ought to give them a good boost toward that first home, and bravo for your willingness to help them out this way.