Hi,
I used to know a chap who worked for an heir hunter. Lost contact now so can not ask him. However, I recall he said that it is easy to claim. Just contact the Treasury informing them you wish to claim on the estate of xyz. They understand not all are in to family history. Any documentation, proof etc will then be requested.
DO NOT sign with these companies, what they do not tell on TV is they claim 60% of your payout!!!
At least that was 6 years ago when he worked for them.
Geoff