Catalysis of the reaction: [1-beta-D-fructofuranosyl-(2->1)-]m+1 alpha-D-glucopyranoside + [1-beta-D-fructofuranosyl-(2->1)-]n+1 alpha-D-glucopyranoside = [1-beta-D-fructofuranosyl-(2->1)-]m alpha-D-glucopyranoside + [1-beta-D-fructofuranosyl-(2->1)-]n+1 beta-D-fructofuranosyl-(2->6)-alpha-D-glucopyranoside (m > 0; n >= 0).