When Did Excalibur Learn That the X-Men Were Still Alive?
The formation of Excalibur was specifically driven by Kitty Pryde and the Nightcrawler (who were both recuperating on Muir Isle from injuries they suffered during the Mutant Massacre) discovering that the X-Men had died without them…
and so they dedicated themselves to form a NEW superhero team to honor the X-Men.
A new superhero team to honor the X-Men
That was Excalibur(along with Captain Britain, Meggan and Rachel Summers).
After the events of Inferno, Rachel discovered that the X-Men were still alive through deep scanning of the mind of her “brother,” Nathan Summers but she decided to keep it a secret from her teammates…
Uncanny X-Men #270
Finally, in Uncanny X-Men #270, with the X-Men dead for roughly 42 issues, the evil Genosha government (who had faced the X-Men soon after the X-Men first showed up alive) revealed to the world that the X-Men were still alive and that the Genosha was considering the X-Men like a rogue enemy state…
Excalibur, though, did not get involved in the X-Titles crossover of 1990, called the X-Tinction Agenda, which saw the mutant teams taking down the evil government of Genosha.
Excalibur #41
In Excalibur #41, fill-in writer Scott Lobdell had Lockheed dealing with surgery. Then, at the end of the issue, it seems like the X-Men had showed up for Lockheed!
The next issue is BIZARRE. The two teams awkwardly interact with each other until they could finally get over the hump and relate to each other as friends and family again…
But then we discover that these were not the X-Men at all, but rather the Warwolves disguised as the X-Men!
Once the battle is over, Kitty and Nightcrawler decide to fight their pride over the X-Men not contacting them and instead they call up the X-Men…
Reunion: Excalibur #57
The reunion is handled off-panel.
However, 16 issues later, the X-Men and Excalibur reunite in Excalibur #57 (by Alan Davis, Scott Lobdell, Joe Madureira and Joe Rubinstein)…
Source: cbr