"Daddy, why is Barbara in bed with you?Where is mom!?!?"
"Dammit, Danielle! Why don't you knock?!?!"
"I don't know, the door was open..."
"You go back to bed..RIGHT NOW!"
SLAM
There go the teeth, falls down the stairs, not bad head injuries, but she is unconcious, and drowns in her noseblood.
Brenda comes in from the garage an hour or so later, and the rest is unwritten history.
I never posted that theory, because the master bedroom location didn't seem to jibe with it.