What does Catholic teaching/theology say about familial relations in hell? This post was triggered by the statement below in History of religion in the Netherlands | Wikipedia:


  Later, In addition to successful sermons, there are failures such as
  the refusal of the heathen Frisian king Radboud to be baptized by
  Wulfram, because he would get to heaven by repenting; Radboud chose an
  afterlife with his ancestors who according Wulfram were in hell.


What does Catholic teaching/theology say, perhaps with scriptural support, about familial relations in hell?

Will the presence of those who were family members on earth aggravate or alleviate the sufferings of other family members in hell?

If I were condemned to hell and God forbid, I met dad, mom, and my brothers and sister, i.e., people I loved on earth,  will this give me any kind of comfort? Will I be "happy" to be with them and they with me? Will we "enjoy" each other's company?
According to the Catholic Church:


  This state of definitive self-exclusion from communion with God and the blessed is called "hell."
  - (CCC 1033)


So hell is not really a physical location but more of a state of being. Thus, although you and your family might all end up in hell, you cannot "meet" them there. It would be like asking if you could meet each other in a state of panic.

While you are dead (ie. before the Last Judgment):


  Immediately after death the souls of those who die in a state of mortal sin descend into hell, where they suffer the punishments of hell, "eternal fire." The chief punishment of hell is eternal separation from God, in whom alone man can possess the life and happiness for which he was created and for which he longs. - (CCC 1035)


On the other hand, you could meet up with your family on the Day of Judgment.


  The resurrection of all the dead, "of both the just and the unjust," will precede the Last Judgment. This will be "the hour when all who are in the tombs will hear [the Son of man's] voice and come forth, those who have done good, to the resurrection of life, and those who have done evil, to the resurrection of judgment."
  - (CCC 1038)


So, for a short time (ie. after hearing His voice, but before the "resurrection of judgment"), you could theoretically meet up with your brothers and sisters. This is what Catholics mean when they say "I believe in [...] the resurrection of the body." This is a physical resurrection, not a spiritual one. So if it's physical, it must happen at a location (unlike "where" your soul goes when you die) and thus meeting up should be possible.

I doubt at that point you would find much comfort in each other's company, but nothing precludes it. You are not prevented from being happy, but by that point you (in theory) understand that you will now spend eternity separated from God and you know what that means (unlike while you were alive).