Don

http://www.answers.com/topic/inheritance has an entry on Jewish inheritance.  It is simplistic to say only sons as males inherited.  In Galatia there would also be Roman and Greek law and Roman law was more favorable to women in general.

http://bible.crosswalk.com/Dictionaries/BakersEvangelicalDictionary/bed.cgi?number=T371 mentions the 3 possibilities which were different.

This is not an area I have studied, but to assert what you have claimed you would need to have statements about how it worked for all 3 types.