Assalaamu alaykum wa rahmatullaahi wa barakaatuhu. When do the children prevent the inheritance the siblings of the deaceased?

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, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

According to the consensus of the scholars, the deceased's siblings are excluded from the inheritance by the existence of the deceased's son or sons . Ibn Al-Munthir wrote, "The scholars unanimously agreed that full-brothers and full-sisters and half-brothers and half-sisters from the father’s side do not inherit if the deceased left a son or a grandson, or even a great-grandson (down to all levels). They also do not inherit if the deceased's father is alive." [Al-Ijmaaʻ]

Allah knows best.