Complex sentence: Frankie realises that the cook and gardener did not see Mr Savage prior to the signing, where the parlourmaid did and she would have realised that it was Roger in the "death-bed" who wrote the will and not Mr Savage.
Split into simpler sentences: Frankie realises that the cook and gardener did not see Mr Savage prior to the signing, where the parlourmaid did. She would have realised that it was Roger in the "death-bed" and not Mr Savage.