I have forty two (42) person at home and when my sisters pray, my nephew and niece come front to pray and I don't know if it is ok because they can't find empty place.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

We would like to clarify the four following matters:

1. If the praying people are praying behind an Imam, the Sutrah (setting something as a partition) of the Imam is a Sutrah for them. So the person can pass between the Imam and the people behind him.

2. Any person praying individually should have a Sutrah in front of him according to the view of the majority of scholars.

3. In principle, it is not lawful to pass in front of a praying person regardless of whether that person is praying to a Sutrah or not. Imam Al-Bukhari reported that the Prophet said: “If while you are praying, somebody intends to pass in front of you, prevent him; and should he insist, prevent him again; and if he insists again, fight with him (i.e. prevent him violently, e.g. pushing him violently), because such a person is (like) a devil." The Prophet also said: “If one knew (the sin) of passing in front of one who is praying, he would rather wait forty (…) than to pass in front of him.” [Al-Bukhari, Muslim, Ahmad, Abu Daawood, At-Tirmithi, An-Nasaa-i and Ibn Maajah] Abu Nadhaar, a sub narrator, said: “I do not know whether he said forty days, or months, or years.” [Al-Bukhari]

Imam Ibn Hajar said: “The above Hadeeth proves that it is forbidden to pass in front of a praying person whether the person can find another passage or not; if he does not have any passage he has to wait till the praying person finishes his prayer.”

4. You should place a Sutrah whenever you perform prayers taking all the precautions to stop children and others from passing in front of you. If in spite of all efforts, they pass in front of you during the prayer, we think Allah will forgive you; Allah willing.

For more benefit on Sutrah, please refer to Fataawa 53945, 84045, 89048, 106812, and 106812.

Allah knows best.