isnt that still a crossover? the fictional Detective John Munch appearing in Doctor Who, pretty much tells us that Doctor Who & Law & Order share the same reality.
Munch appeared on X-Files
and L&O, yet those two shows obviously do not share a 'verse.
- which *does* share a continuity with L&O - has already established that XF is fictional within it. So therefore XF is fictional in L&O as well. The fact that Munch appeared in both, is irrelevant.