Theofonias said:
At lexicanum I found a short list of which Chapters have been known to contribute to Deathwatch.
- Black Consuls
- Black Templar
- Blood Angels
- Blood Ravens
- Crimson Fists
- Death Spectres
- Exorcists
- Imperial Fists
- Lamenters
- Mantis Warriors
- Raven Guard
- Red Talons
- Revilers
- Salamanders
- Scythes of the Emperor
- Space Wolves
- Ultramarines
- White Scars
So far they have been following this list with the exception of the Dark Angels. Which only makes sense because they are right next door to Calixis.
The setting isn't anywhere near Calixis though. And the Dark Angels don't have a homeworld anymore, so they can easily be anywhere for narrative convenience.