I think the quotes I added above direct from HCW should be clear enough to explain the link between HB and the MM case. They show precedent and MO combined with other circumstantial evidence they have against CB. HCW has shown he can successfully do this with a no-body murder. Why do you think they are going for these 5 charges first?
The clear link between CB and the case of MM is opportunity (no alibi, proximity to the area, knowledge of the area , ping) motive (chats, convicted sex abuser of children and vulnerable people) and means (known burglar, the MO used in the other cases, or maybe even described in these said autobiographical books that CB had tried to destroy and/or in the chats and the witness statements which could all link back to the autobiographical books and witness statements- if CB had written/discussed/boasted about these other crimes for which he would be convicted then presumably what he said/wrote about MM would also be true and thus these cases could set a precedent for the inclusion and permissibility of this type of evidence for the case of MM .
Jmo