Can a boy be sent back from the first row if he joins it?

No File Exists
Check below answers in case you are looking for other related questions:
Praying in a mosque which is attached to a grave in the direction of the Qiblah
Prayer rooms (musallas) in houses and businesses do not come under the same rulings as mosques

No File Exists
Related Answers:
Does the multiplied reward for prayers apply only to the mosque of the Ka’bah or does it include the entire Haram (sanctuary)?
Building a masjid in a place where it is not expected Muslims will remain permanently is permissible
The University is giving them a prayer room for them and for others who are kaafirs
Praying in a mosque which is attached to a grave in the direction of the Qiblah
Prayer rooms (musallas) in houses and businesses do not come under the same rulings as mosques

Recommended answers for you:
The limits within which a married couple may enjoy intimacy with one another, and the ruling on a man suckling from his wife
Sleeping after Fajr and ‘Asr
What is the true meaning of shirk and what are its types?
Why does Islam forbid lesbianism and homosexuality?
What are the rights of the husband and what are the rights of the wife?