In The Others (2001), when Grace entered the room where Anne was playing wearing a wedding dress, she saw an old lady's hand and face behind the veil of the dress. Whom did she see? Was it that old lady who was staying with Victor's family?
That was spirit medium. What Grace saw was the "outside" part of mediumship. Anne has possesed medium and talked to participants of the show. At the same time the medium have been "transfered" to the Grace plane.
Adn yes, the old lady was that medium that tried to help Victor family to connect to ghosts.