Disabled Parking ? UK???? HELP.?

If his daughter in law does not have a Blue Badge {UK} or a authorised disabled sticker she is not allowed to park on a disabled bay. If you neighbours wife no longer has a disabled badge she cannot park on that disabled place. If the husband has a separate car, not used by his wife he can not park on that disabled space. Any car parked in that space should be displaying a legitimate disabled badge.
If you think the wife is abusing a disabled badge i.e she has obtained one under false pretences or her condition has improved since she obtained it you can report you doubts to the badge issuing section of you local county council (find it on Google)

That is what you CAN do but end of day they are still your neighbours and you must live alongside them day in day out.
The final thing to remember is the road outside a property does note belong to the resident and any road legal car can park there if no restrictions apply so long as they are not causing an obstruction to traffic flow.

There are many reasons to issue a disabled parking permit, and the disability isn't always visible.

To park in a disabled space, a disability permit must be displayed. As long as that's displayed, either car can use the space. Unless otherwise specified by a sign and writing on the space, it's not solely their space, either. Any disabled permit holder can park there, so"place-holding" is commonplace and perhaps understandable.

The only grounds for complaint are if the vehicle displaying the disabled badge is not being used to carry the disabled person. Unless the disabled person no longer lives at that address, or unless that person is staying elsewhere (such as when on holiday or as a hospital in-patient) proving misuse of the badge is very difficult.