You can try another approach. Rename all files to mytags
and use different paths to get them. like:
~/.vim/tags/boost_filesystem_1_55_0/mytags
~/.vim/tags/boost_program_options_1_55_0/mytags
~/.vim/tags/zlib_1_2_8/mytags
...
And as value of tags
use ~/.vim/tags/**/mytags