Historical records of changes to date of birth

born_again

Could it be as simple as the person that died, bank account, has been transferred/taken over by the other person?

Far more to this that meets the eye.
Why would someone have someone else's cards? Were they vulnerable? Did the other party have POA or were they simply a fraudster pretending to be a friend.

jbuchanangb

It may be coming to some sort of attempted fraud by the person referred to as Mr B. Friend. It is important to find out the nature of the joint ownership of the property between Mr A. Friend and Miss Friend. https://www.gov.uk/joint-property-ownership is a helpful reference. If it is "Joint Tenants" then the property becomes wholly owned by Mr A. Friend on Miss Friend's death. If it is "Tenants in Common" the the ownership of Miss Friend's share will have to be distributed by her executors in accordance with the laws of intestacy. 

"Joint Tenants" is usual with couples, "Tenants in Common" is more likely with siblings.

Neither of these situations looks like giving the estate of Mr B. Friend any claim on Miss Friend's share of the property. It is possible that the property will have to be sold by the executors of Miss Friend, with Mr A. Friend receiving the value of his share, and the value of Miss Friend's share forming part of her estate and the then distributed according to the intestacy rules. 

someone

the key bit of help and thought i am looking for is, how could Mr B Friend have had the DOB of the account held by my friend and his sister, changed, to his DOB.  

Take it as a given that the records could be wrong. I've hear of all sorts of mistakes and errors to have been made that you would think are impossible or should be "never events". Case in point, my Mum & Dad had over time taken out endowment policies in turn with each others life insured. The final policy was still to mature when by Dad died. Letters from the last 15+ years had said it was a policy owned by my Mum with my Dads live insured yet when when we went to find the policy certificate found the NAMES THE OTHER WAY ROUND! On checking the letters we found the year that the switch occurred (looked like they had an IT upgrade as the style was different). We complained and received a small amount of compensation, we pushed for assurances they would audit other policies but they never committed to doing this.

If you have legal advice on your home insurance, via work or union membership I would look at using that. If so I would strongly suggest jbuchanangb post  is how you introduce the problem to anyone providing you further advice or guidance.