Avalanche's wife?

She was invented in the 1980's Marvel Handbooks, but has never been seen or even referenced in regular continuity, TMK.

Damned if I know.

Avalanche's mysterious wife isn't the only spouse referenced in a Handbook but never appeared / mentioned in continuity - Diamond Lil's entry in the OHOTMU Deluxe Edition listed her as having an ex-husband.

Surprisingly enough, no. These are from the original OHOTMU editions produced in the 1980's and compiled by Mark Gruenwald, Marvel's original continuity cop.

I don't remember any new handbook discussing Acolytes in the way Mark is talking about...perhaps its something from the 90s?

Originally posted by Binaryan It seems to be common practice for the current Handbook writers to fill in the blanks on certain character details that are never likely to be touched upon again.  The most common examples seem to be real names and defined power sets for characters who are unlikely to ever be used again or revisited.  A lot of the dead Morlocks, X-Students and depowered mutants were handled this way in the most recent volumes of the Handbooks. Occasionally, they add in other tidbits that address more significant continuity issues but have never actually been addressed in print.  For example, the entry for Wanda & Pietro included that the High Evolutionary placed them into stasis as children explaining how they could have been born shortly after Magneto's power emerged... which was only a few years after WWII ended.

The current handbooks do sometimes fill in the blanks on certain character details. However, so did the originals - it has always been something the handbooks did. Generally, things like confirming real names will be considered if others use the same codename, as a way of differentiating between those characters. Sometimes new information arises as a result of trying to clarify continuity clashes - for example, how Humbug went from being apparently killed by being fed to fire ants and then alive and well without explanation in Heroes for Hire. In such cases the first port of call, when they are available to contact (e.g. not dead or otherwise incommunicado) are the writers who created the character or wrote the relevant stories (and if writers aren't available we'll try the editors of said stories). And they always have the option of "leave it unexplained / unrevealed" - in which case an entry will list names as unrevealed, or say something like "Somehow surviving, Humbug..."

Sometimes scripts are available, and so can provide additional clarification. As I mentioned in a post in the corrections forum, there is no Turner Scholl in the Hellfire Club - there's Turner, a thin man with long hair and a ponytail who was skewered by Castlemere in X-Men Legacy #515 and confirmed as having been slain both visually and verbally, and Scholl, who (in his human form) was a stocky and bald ally of Castlemere who first appeared in X-Men Legacy #517. The most recent Hellfire Club entry in the handbooks identifies Scholl as Peter Scholl, a.k.a. Leonine, as both his first name and codename were provided in the script for X-Men Legacy #517.

Potential new information, whatever the source it comes from, is run by senior editorial (generally Tom Brevoort), who either okays or rejects it being used.

The above is the same system the original handbooks used. So it's inaccurate to say that "the more recent handbook editions that have taken more liberties with continuity". Check how many "established" character names, both minor and major, were actually first given in the original handbooks - just as a small sampling, first names for Zarkko the Tomorrow Man, Scarlet Scarab and Living Monolith, real names for High Evolutionary, Unus, Toad and several of the Squadron Supreme, and codenames for several of the Imperial Guard. And the original handbooks were much quicker to fill in blanks in character histories - the current ones only attempt to resolve continuity conflicts, and anything beyond that (origins for example) tends to have been actively volunteered by the writers of the characters in question.

It's also worth noting that, not infrequently, what people think is new information revealed in the handbooks is actually information from a story that person hasn't read - such as the time someone on another forum took the handbooks to task for "creating" an identical twin brother for the Enforcer's Ox, unaware that was something the comics had established back in 1978.