Yeah... canonically, Guinan was at the wedding reception in NEM, and I guess that means she was also in A Time for War, A Time for Peace
. And of course she had a sizeable role in Greater Than the Sum
. And that's just if we're talking in-universe chronology. She's been in several works published after GEN came out, including Stargazer: Oblivion, The Buried Age
, and a couple of stories in anthologies.