I know you're just trying to pull something out of thin air that sounds plausible, but...this would be simple to prove with a request for valid death certificates, marriage license, and a birth certificate to prove you were married, the child is yours, and that both are in fact deceased. Oh, and of course, you'll have to prove who you are as well.
Given the (rightful) outcry about handing out your IDs to private corporations in "safety"'s name, are you really suggesting providing documents even more specific about you?
We're all worried about identity fraud, and such documents are actually used to apply for an id in some countries!
To be sure, it would suck trying to do all of this for some web service. I've had to do it for something more substantial like insurance. I wouldn't think this kind of thing should be a scan and upload to a cloud bucket. At this point, we've reached a human, and should be able to deliver physical documents to said human
It may be simple enough to prove, but that is an uncomfortable ask if those circumstances are genuine.
If these were truly the only copies of photos as in the example, then you'd probably be willing though.