@Steve Borodin. I would deny them based on poor credit to avoid any issues with discrimination. Six kids with a sick mother will cause damage to your property. The mother will be busy getting her treatments and resting and not properly supervise them. The dad will be busy working and trying to keep his sanity with a sick wife and six kids.
And they may fall behind on rent due to medical costs and buying takeout food when no one has the energy to cook. And the dad May have a problem keeping a job too with all of his family responsibilities and new employers not usually being accommodating of time off requests. You already feel bad about denying them so would you really evict them when they start paying late and the. Miss a rent payment and come to you with a sad story about why they will need to pay later.
It would be a bad business decision to accept them. Deny their application and find someone whom will
be able to pay the rent and take better care of your property.