Do you know them personally or is this third hand. As long as they all are well cared for and have freedom to roam indoors, and they don't spend their lives shut up in cages, not all cats have to go outside, 'better to be inside and fat than outside and flat'!! Is there someone that can keep an eye, that perhaps visits the house on occasions and sees the animals on a regular basis, close family friend perhaps. If there is reason to believe the animals are suffering then of couse an outside welfare organisation must be contacted.