I believe Moonlight Magic limits eligibility to the membership used for the reservation. For example, I have one direct blue card eligible membership and one ineligible membership (two different membership numbers). I booked stays for my family and another, one from points in each contract, and I went to book Moonlight Magic. I was told that because the second room was booked with an ineligible membership that I could not include that room in my Moonlight Magic reservation. My understanding is that in the future my own eligibility for Moonlight Magic will depend on the source of points used.
Maybe the TOTWL will be similar and it will matter what pool of points are used to determine eligibility? That could explain what they're doing with "within your membership," some new way to limit resale contracts so people don't just buy minimum direct and go resale for balance? (For people with resale direct in same membership ID, it probably wouldn't matter, but may matter to people like me with multiple memberships).