If Ralph was tied up, or tethered to anything, at any stage before the actual shootings got underway, it would have made it a lot easier for someone like Sheila to control him, and dare I say it, free up sufficient time for her to kill the others. In my view, this would fit into the mindset which Sheila had fallen into, on the previous evening, when her parents were suggesting that she wasn't fit or well enough to look after her own children. The thought of having her children took off her, or losing them, could have sent her over the edge - with this in mind, did Sheila manage to catch Ralph unaware, and tie him up, whilst she went about shooting the other victims?
Seems like a plausible scenario to me...
Tying up Ralph, and thus restricting his ability to protect the others and himself, makes perfect sense in the circumstances of this case. Sheila shot and killed her mother, shooting her whilst she lay in bed. Sheila shot and killed her children whilst both slept soundly in their beds in an adjoining bedroom. At some stage afterwards, Ralph was freed up, or untied at the point of a gun, and forced to make a telephone call to Jeremy to try to lure him to the farmhouse, so that Sheila could kill him, as well. It is perfectly feasible that when Ralph had made the call to Jeremy, that he took the opportunity to break free from Sheila-s control, and that he then managed to call the police to alert them about what was happening at the farmhouse...
