Re the liver function. Maybe RB wanted to know it was safe to dose the women with drugs? JO said she felt drugged the night of the photographs. Maybe he wanted to keep slowly poisoning or ad hoc drugging women but be assured that they wouldn't end up actually dead because they have a liver problem - he's a control freak quite clearly and I imagine having an accidentally dead woman on your hands would mean instantaneous blowing of his cover, detaining by the police, and possibly life in prison. He wasn't with the women consistently day in day out but maybe he was drip feed poisoning them in a way that would culminate in death at some point in the future, ie arsenic or suchlike?
Maybe there's poisoning that means that a victim could end up feeling really poorly and feeble for weeks / months and slowly decline ending up dead in due course - then he gets everything as he's taken possession and power of attorney. What do we know about any women who checked into hospitals, A&E, or were found deceased alone but not in suspicious circumstances? What if Marion died alone in a lodging room or hotel but with someone else's paperwork and the death wasn't considered suspicious? How far down the line do the police / authorities go to 'detect' such things? A close relative of mine died suddenly at home alone recently and to say the powers that be could not give a monkeys about what happened is to put it mildly. They are very satisfied to say 'heart attack' or such with eff all investigation when someone is over 50 and there's no sign of a struggle or forced entry.
Or maybe he was drip feeding some kind of drug that meant the women would become 'addicted' to him without realising they were not feeling amazing in his company, they were being doped?