wa'alikum as'salaam,
Proper Islamic guidlines dictate that you can lead them in salah and they can follow you behind but you can't stand side by side and do salah together that way. In a jammah, men are always behind the imam followed by a line of children followed by line of women. children can be on the end sides of the lines or behind the men, some people like to have their prepubescent kids stand next to them, this breaks the chain formed by worshipers standing in line and should be avoided.