Banshee (Sean Cassidy) is the father of Siryn (Theresa Rourke) who is a former member of X-Force. Sean has a slightly strained relationship with his daughter as he was not present while she was growing up, through no fault of his own. He is also the cousin of Black Tom (Thomas Cassidy), who raised Theresa and views her as a daughter.
Both of the White Queen's siblings have appeared in Generation X. Emma's older sister, Adrienne Frost, helped with the Academy's finances during a rough period, later tried to kill the GenXer's, caused the death of Synch and was eventuallly killed by Emma. The younger sister, Cordelia, was involved with Mondo and came to Emma for help.
Paige Guthrie is the younger sister of Samuel Guthrie (aka Cannonball). Sam is a former member of X-Force and the X-Men.
While this is not strictly all family, it does involve Jubilee's family. Her parents were murdered by two assassins hired by the grandfather of Tristan Brawn (Husk's former boyfriend.)
The most complicated family of all. The real M is the sister of Marius St. Croix (aka Emplate) and Nicole and Claudette St. Croix. For a time Nicole and Claudette posed as Monet, when Marius trapped her in the deaf, mute Penance body. Monet was eventually returned to her own body. Marius killed their mother when his mutant powers first surfaced by feeding on her bone marrow.
Chamber & Jubilee
As far as I know, these two don't have a problem with each other but they're not close friends either.
Chamber & M
Since Monet doesn't have much of a friendship with anyone, besides Ev, it's impossible to know what Jono and M think of each other.
Chamber & Skin
Jono and Ange are pretty good friends. When Jono was having problems with his powers, during the Onslaught crisis, Skin tried to bring him to Westchester to Professor Xavier. Later Jono helped Skin in LA, even though Skin didn't explain what he was doing. At one stage Chamber was slightly jealous of Ange's friendship with Paige, and read too much into it but that was soon cleared up.
Chamber & Synch
Ev and Jono were also fairly good friends. But Ev was so easy going he got along with everyone. The two went shopping for tuxes together before the school dance.
Husk & M
Paige and Monet don't really have a relationship, and don't seem to have held many conversations with each other in the past. That may change in the future, though.
Husk & Skin
In the beginning of Generation X it was hinted that Paige and Ange may get together, and were quite close friends. However that idea seems to have been abandoned and they remain merely friends.
Husk & Synch
These two seem to have had practically no relationship. We haven't seen them interacting much and it was never clear what their opinion of each other was.
Jubilee & Skin
Ange and Jubes are friends, nothing more and nothing less. According to some there is a possibility of romance between the two, but the characters have never expressed much interest in each other in that way.
M & Synch
Although Monet and Ev were never really good friends, he was probably the closest thing she has ever had to a best friend. Ev had a crush on Monet for a long time, beginning around issue #30 when they kissed. However that M was the twins posing as her and not the real one. The next kiss that we saw was in issue #67 between Ev and the real Monet, revealing that they began dating during the 6 month gap. She seems have been the most affected by his death and is still grieving for him 6 months later.
Skin & Synch
Ev and Ange got along fairly well, then again Ev got along well enough with everyone. Anyway, they have never had any real problem with each other in the past.