The twins were born in 1897. Marian Lamb Bechtelheimer died in 2002 aged 105years. This is documented by IMDb. The other one, Mary Elizabeth Sheridan, does not have a date of death on her page.
Does this mean she is alive and 108years old? Wouldn't you expect IMDb to have the date of passing of either both or none, leaving the door open that one would still be alive?
Actually I have no idea whether the other one is still alive, but I'd think, as you said, IMDb would either have the passing date of both or none... but I can't believe the one twin is 108 years old? She'd be famous (and if only a little), wouldn't she?
I am placing my mind elsewhere while you chatter away. - The Remains of the Day
108 is not out of the question. Frederica Sagor Maas (Hollywood writer) will be 107 years this year. French actress Madeleine Milhaud will be 105 years in two months. French actress Germaine Auger made it too 112!
But yes, we are thinking alike in saying that if IMDb was given, or found out, the recent death date of one sister you'd think they would know, or be informed of, the other's.