Zsh, 58 bytes
b=${(j::)${(os::)2:l}// }
<<<${${(j::)${(os::)1:l}// }/$b}
Similar to my other anagram solution, again using Zsh's gnarly parameter expansion. Added a few bits to lowercase everything and parse out spaces. Tried to jam everything into one fancy expression but Zsh kept complaining, so I separated out $b to make it work.