I saw a speculative theory on social media that Woodward is trying to facilitate a move for Depay or Zaha to Dortmund as a replacement for Sancho. If we have a sell-on clause in those contracts (e.g. for 25% or resale value as reported here
https://www.football365.com/news/wilfried-zaha-deja-vu-man-utd-transfer-clause-palace-price), and Dortmund uses our cash to buy one for 60m euros, that would reduce our effective outlay by about 15m and could make the deal doable. You could even imagine a type of scenario where Dortmund sell Sancho to us, Palace sell Zaha to Dortmund, and we give Palace Lingard (or other deadwood) on the cheap to facilitate the whole thing.
Don't know if any of this is true, but the theory would make some sense and potentially explain why the whole thing is taking so long. It would take a lot longer to negotiate multiple transfers in parallel than just to do a single deal.