
In the pages of Excalibur, which was also written by Chris Claremont, Storm’s squad of X-Men were helping Excalibur prevent the Weaponeers from conquering Zanzibar. The UxM HoM tie in starts there, but when the “white flash” happens in House of M #1, Rachel Grey’s powers react instinctively and shunt her and Psylocke over to a pocket dimension controlled by the Phoenix Force.

While a bunch of the UxM cast get thrust into the House of M world in various ways, Psylocke and Betsy try to prevent the total destruction of Earth 616 while also navigating the House of M universe.
I know a lot of fans, especially the Fandom web site (which is kind of an unofficial bible), say that the characters appearing in House of M aren’t the 616 versions, and I *think* that’s true for at least some of them—but others, no. They’re 616 characters manifesting in Scarlet Witch’s reality. At the same time, they’re not all like that–some are projections of the thoughts, fears, dreams, etc. of 616 characters. That’s how we can explain the existence of Gwen Stacy, e.g.
So it’s my view that only Psylocke and Marvel Girl can clearly be identified as 616 characters in this story. Anyway, that’s a long way of explaining why those two are character tagged.
It’s not surprising that the flagship X-title does more than just have a fanciful “What If?” story, but sadly it does do that. It just also does a little more.
Next: Decimation