The "accepted wisdom" on the Filipina is from Sheridan's smartvoter pages..
Sheridan says
In 1977 Peterson and the children drove to Tehran, Iran. His wife, who had returned to the Philippines to care for an ailing mother, died of pneumonia.
The idea that the woman returned to care for her mother, makes sense to me. I don't see why Sheridan would make up that detail.
And I can't see Sheridan taking care of kids at a very young age. By this time, they would be 7 and 5, so if the mom died, I could see Sheridan managing things.
I think it's most likely the Filipina did die as Sheridan says. Sheridan puts in unnecessary detail, when it's true.