ANSWER:
Al hamdu lillah!
May Allah ease your calamity and comfort your heart with tranquility.
Without a doubt, they will be a barrier for you and their father from hellfire and you will be reunited with them in paradise.
This is a test from Allah and losing 2 only suffices and they would take your hand on the day of judgment and pull you to paradise as per the hadeeth! Losing 4 would double such chances providing you are patient and content with Allah’s decree.
May Allah reward you and grant you better than them in this life and in the hereafter.