Answered by Shaykh Abdul-Karim Yahya, SunniPath Academy Teacher
What is the position of the Shafi’i school on female congregation? An earlier post says something about it being permissible to join a congregation but it doesn’t specify an all female congregation like the Hanafi answers do.
In The Name of Allah, Most merciful and compassionate
It is permissible for a woman to be the imam of an all female congregation because this was authentically transmitted from the actions of our ladies ‘Aisha and Umm Salma, Allah be pleased with them.
It is praiseworthy for a female imam to stand amidst them with those in the first row on either side of her.
The toes of the women in the first row should begin immediately behind her heal.
And Allah knows best and He alone gives success (tawfiq).
 See: Ibn Hajar al-Haytami, Hawashi al-Sharwani Wa Ibn Qasim al-Abbadi ‘Ala Tuhfah al-Muhtaj Bisharh al-Minhaj (Beruit, Dar Ihya’ al-Turath al-‘Arabi), 2:310.