Who Did Lila Kedrova Play?

i think Lilia Skala was the piano teacher.
One person i have always wondered about is when you see Brad go to Henry's house and you see the wife in the room where the main door is. Next to her is soem woman who is not even acknowledged by Brad or introduced by Henry's wife. This is the part where as Brad walks towards Henry's radio room, you hear Henry talkign offscreen and he mentions that maybe it was Russians or Chinese who started it. i know it is not Lila but still wonder who it was.
My guess is Lila is Carol moms voice on the answering machine.