Children in the Musjid

Q: There is a man who brings his small son to the masjid. The na baaligh son wears shorts and his knees are exposed. Is this permissible?

Q: Can small children (non baaligh) stand at the end of the adult staff where an adult cannot stand due to musalla being small?

Q: I wanted to ask the mas'alah regarding children standing in saffs with the men. I always knew that small boys should stand behind the saffs of the men. However, I have noticed a trend of small boys standing next to their fathers.

It just worries me and I am inconvenienced at these small boys standing beside me in the saff. Please advise and guide as to what is correct according to Shariah.

Q: If there is only one child for salaah, must he stand in his own saff or must he stand in the adult saff?

Q: We have children who are not baaliqh attending the fardh salaah. They are standing next to their fathers in the first saff. They were requested on many occasions to have their sons read in the back saff.

Is my salaah nullified? Is it makrooh to have these young boys in the middle of the saff?

Q: What is the Shar'ee ruling regarding children standing in the first saff for salaah? Is this permissible?