Early SH:R Concept Work Commissioned by Roger Avary

[The Demon]

This is an idea I'd kind of hoped they might go for in SH:R... although it could be cheesy if not done right.

Let's say Heather, after escaping Silent Hill, has lived a relatively normal life. However, at several points in her life, she has experienced strange "seizures" if you will. During these seizures, some kind of tragedy or catastrophe happens around her. Every time one of these has happened, Chris has uprooted their family, moved and created new identities for them.
As we find out in the film, these seizures Heather has are actually periods when the Darkness comes. Heather is overcome by a massive headache and collapses, and then the Otherworld takes over the Real World around her. Anyone in her vicinity is pulled into the Otherworld as well (and most likely butchered by its' inhabitants). The Real World companion to these events is some kind of catastrophe (like a building burning down), which would provide an explanation to the deaths and missing bodies. Only Heather would ever survive these, and Chris, desperate to keep Silent Hill from reaching his family again, flees and reconstructs new identities for them to keep anything or anyone from Silent Hill from finding them.

Perhaps these Otherworld events are triggered by things that remind Heather of Silent Hill, maybe the arrival of a Cult member into her vicinity.