I'm not sure how it worked for others, but I had 2 ready to collect when part 10 started so I only had to make 3/5. And while I was making the nests and blankets to complete part 10, I kept making food too and they all count towards the part 11 upgrade. 17 more nests and 8 more food to finish this PITA!
*make that 15 nests, 7 food.