“Heichan Matzinu that an Isha can make any brocha that requires a minyan to say it,”
Are you certain a minyan is required to say the last 2 of the “sheva brachos”. See the many rishonim on the sugya in kesubos who say if the chassan is eating alone he says the bracha.
I dont know what the psak is. I do know what the minhag is. The minhag is that someone, other than the chassan and kallah say all the brachos, despite the fact that they might be birchas hashevach.