The title - Wyrd Sisters has a meaning that some readers might not have 'got'.
Wyrd is an Anglo-Saxon word meaning 'fate'.
Here's the Wikipedia for Wyrd.
In Norse mythology the Fates, or Norns were three female weavers who controlled the destiny of men.
The whole idea of Wyrd Sisters refers to this I think - with our trio playing that role. This is not just a Shakespearean allusion.
*Fate remains wholly inexorable