Unpack this legal gobbledygook: Monetary compensation - Who gets what?

Question

Legal Advice from a big insurance company:

- One-half to his mother, if living, if not to his father, and one-half to his mother-in-law, if living, if not to his mother, if living, if not to his father.
Thereafter payment is to be made in a single sum to his brothers. On the one-half payable to his mother, if living, if not to his father, he does not bring in his mother-in-law as the next payee to receive, although on the one-half to his mother-in-law, he does bring in the mother or father.

Answer 1

~If alive alive, mom gets half, unless mother in law is dead, in which case mom gets all. If she's dead, dad gets half unless mom-in law is dead, in which case he gets it all. Of course, if all three are worm food, the male siblings split the pot. Wherein lies the difficulty?