I am using Atahualpa also, I tried the Template: bp-sn-parent thing in the style.css of Atahulpa but no go.
I was able to get it to work by adding all of the directories (folders) from the bp-sn-parent theme to the Atahualpa theme. Also I could not @import the style sheets for the adminbar.css, but if you paste the css from both adminbar.css (parent and default) into the css section of Atahualpa’s ‘Add HTML/CSS Inserts’ then the theme works.
I have not yet figured out how to get the user menus for MEMBERS GROUPS BLOG ect.. to show. Any help with that would be appreciated.