Depending on your operation and personnel you may want to set the axu to POST fade.
You can still go to those mix sends and set the balance needed for live stream but being
set POST FADE the mix changes made to the main mix will track along to the live stream mix but at the proportion you set on the mix sends for live stream.
If set PRE FADE you would need to be actively mixing the main the live stream mix at the same time.
If you have a second sound person then they could be in a separate room monitoring and mixing the live stream or at least wearing good sealing headphones while mixing the live
stream.
If you just want to duplicate the main mix as it is and send it to the live stream think about using a matrix mix output, that would still give you the additional level, EQ and compression options.