The Gods guard, guide and protect the souls of all the loved ones of Satanists, it is in fact something they take seriously to the highest degree, I asked this same question to my GD and the response I got was the strongest response to any prayer I have ever had, it wasn't just a yes it was a yes with absolute conviction which left no room for doubt this is something they have been doing for a long time and they know exactly what they are doing, your loved ones in death will get what they need from the Gods, eventually they will be reincarnated and reborn as they have time again and again before, those of Satan do not die for our souls are kept by him and rebirthed again and again until we achieve the Magnum Opus, even those who are without are for the most part claimed by the Gods it is only the damned who are not and they did that to themselves.
I dont think the death of loved ones will ever not bother us no matter how advanced we become, I know that when my parents go I will never stop missing them even if I achieve the magnum opus but death is a reality of life and my parents will live again and if I do achieve my goals I will be able to watch guide and guard them personally for eternity, incarnation after incarnation and one day reunite with them when they are ready to join me, I use this thought to help fuel me when I feel I might not be able to achieve my goal of the magnum opus, perhaps it will help you do the same.
There are also blessings you can do as a Satanist to aid those who depart, these spells are not yet on the JoS but I dont doubt one day they will be, furthermore you can always do the rituals of Anubis and start forming a positive relationship with him, yet again he takes his role with absolute dedication hopefully feeling his power will bring you some reassurance as to the dedication the Gods of the afterlife have for our souls.
I have a lot of speculation that we can do a lot to help our families in the afterlife but I wont speculate as the clergy will likely clarify these topics in the future with more knowledge than me.