[AltaRed]

The trustee would have to be the FI meeting what the signed beneficiary form said. The Executor has no right to 'touch' a registered account with a named beneficiary.

However, I agree Ian needs to clarify what 'transferred' means. I took it to mean successor annuitant.

 

[AltaRed]

I doubt it can be reversed since your sister was alive at time of BIL death and presumably already received the account as 'successor annuitant'. Sometimes there are provisions to handle a simultaneous death, or a successor death within 30 days, but not after that. I am no expert on this though. I think a lawyer may have to address this.