Changing citizenship between EEA2 is issued and EEA4 applic

I have a quick question about what would happen if I person were to change citizenship between their EEA2 application had been approved and before they applied for EEA4 (PR).

It may be easier to provide an example:
Mr A is an Italian citizen and is married to Mrs B, a Japanese citizen. They live in the UK and Mrs B has already been granted a residence card as the family member of an EEA citizen. Mrs B has recently been approved for Italian citizenship and will lose her Japanese citizenship as soon as she takes on Italian citizenship (automatic loss of citizenship).

Is this case, is it still possible for Mrs B to apply for PR in the UK (via form EEA4) if she is not holding her Japanese citizenship/passport, which was used for her to apply for EEA2 in the past? The Home Office won't hold any records of her as an Italian citizen.

Does it make a difference if the person's citizenship changes, even though the person is actually the same person and can provide a copy of their old passport to show that they are one and the same?

Thanks a lot
C
PS: Please don't delve too much into the fictitious situation that I have invented above...it's only provided for illustration purposes.