I will always wonder how we got from "I told them no no no, this can't happen very often" (

) to Madeline being literally forced by JS to sleep with SS -- not even just to sleep in her own cot/on the couch downstairs, but specifically in his bed in Room #4 -- despite Madeline begging JS for them all to sleep together, that one fateful night (most likely in an effort to avoid the continued abuse she knew was coming if he managed to get her alone).
This is why I will always believe JS was complicit. No good parent goes from that first extreme to the other. Not only that, but if she was truly worried about losing him to the Woody Allen scenario, why would she force it? There are few explanations, and none of them good.
If they lived in that condo that whole time (pretty sure they did), then, at some point, there absolutely must have been options for Madeline other than Room #4, when JS apparently needed her sleep. There's no getting around the fact that JS made any/all of those no longer an option by the time of these events, because she specifically forced Madeline to go sleep with SS in Room #4, despite Madeline's pleas to the contrary.