please set manuale db set for blogs in new version of wp

hi

please set manuale db set for blogs in new version of wp multisite.

I use multi-db(16db)plugin but it copy any table from example blog 12 to different db.
wp_12_posts >> wpmu_0
wp_12_postmeta >> wpmu_f
wp_12_setting >> wpmu_b

if wp core have possibility for admins to set for any blog 1 new db,it is very useful.