I feel very embarassed for saying this, but according to Emily Post (who lives according to Emily Post) it is NOT the bridal party's responsibility.
Who can throw a Bridal Shower?
Traditionally, bridal shower etiquette says that close family members of the bride (sisters and moms) are not supposed to throw a shower for the bride. But, for many brides, there simply is no one else who can or is willing to do it. Therefore, anyone who wants to throw a shower can, bearing in mind that if there are plenty of people who would like to throw a shower for the bride, then the mother and sisters should take a backseat. Bridesmaids do traditionally throw the bride a shower.
Your friends probably want to share in your wedding, but since they can;t make it this is the best way for them to honor you. You have great friends! Let them celebrate you!!!