A Muslim son may see his Muslim father in Paradise and join him in his rank if it is higher, just as a father will join his son in rank if it is higher than his father's. This takes place as a bounty from Allaah to His slaves. Allaah Says (what means): {And those who believed and whose descendants followed them in faith - We will join with them their descendants, and We will not deprive them of anything of their deeds. Every person, for what he earned, is retained.}[Quran 52:21]

Commenting on this verse, Ibn Katheer stated that it affirms that if the descendants follow their believing parents in faith and will join their parents in their rank in Paradise. They will be at the highest levels of eternal bliss where they converse and remember the hardships and difficulties they encountered in the worldly life. They will praise Allaah for such joy; Allaah the Almighty Says (what means): {And they will approach one another, inquiring of each other.}[Quran 37:50]   

Allaah Knows best.