What is the ruling on congregational prayer with girls, and does it count as a valid congregation? What is the ruling on my son leading us in prayer as an Imam? Is it permissible for my sister to join us in congregational prayer? What is the ruling on congregational prayer in the women's prayer area in the garden? And what is the most preferable in these situations?

The ruling on a woman leading other women in prayer has been previously clarified. As for a discerning boy leading obligatory prayers, there is a difference of opinion among scholars; some have prohibited it, while others have permitted it, citing the hadith (definition) of Amr ibn Salamah: "I led prayers during the time of the Messenger of Allah, peace and blessings be upon him, when I was a boy of seven years." The preponderant opinion is the permissibility of a boy leading prayers. Therefore, there is no harm upon you or your sister if you pray in congregation with him.