This is how I see it. SH stoked NM's fantasies started by underage *advertiser censored*, in attempt to please she texts him suggestively about abductions. SH attempts to initiate a 3some with the girl from NM's work, but it comes to nothing. NM feels frustrated. Meanwhile SH dislikes becky, feels she is draining money from parents which is rightfully SH & NM's (hence talk about wills, clothes, becky not respecting electrical items she was bought). NM and SH discuss abducting a school girl, buy stun guns x2 and handcuffs. NM is reaching a sexual frustration peak as missed opportunities (girl in the shop) and SH feeding hatred of becky into his ear (jealousy, as she is aware NM has some sexual attraction to Becky.) Something ignites NM into action (??? maybe to be released after the trial) and after he discoveres Anje is going to hospital leaving Becky alone, he takes this opportunity. SH willingly wanting to see Becky damaged (rape/violent abduction is probable). They enter the house, NM full of adrenaline goes straight upstairs with mask on (not thinking becky will instantly recognise him due to his short height). Becky starts screaming, shouting down to SH and fighting. With no tools to help subdue her (handcuffs and stuns downstairs) and B recognising him (he wasn't counting on this) further inflaming NM's frustration, he smothers her (to teach her a lesson not to stop his plans) and goes down to tell SH. This is further than their initial plan,however hatred of becky and adrenaline, plus obsession with NM means SH readily accepts the situation and plan the disposal etc. They put body into the boot of the car and sit down to discuss their alibi and exit plan. They return home, research on their phones (how to get rid of a body) and attempt to cut her up with a knife (back of leg wound) and realise it's harder than first thought. Stabbing abdomen in frustration and annoyance that Becky has ruined their perfect fantasy. NM buys saw and dismembers. SH enjoying their shared secret (jokey text about being "long at work lol" when buying saw) NM Contacts friends who willingly help, thinking it's drugs or stolen items, (realising its not pretty quickly, but it's too late, they have already implicated themselves by fingerprints on the bags, so sit tight). Police become suspicious because NM and SH do not help and have bleached bathroom in messy house and last people to see her alive. then fingerprint in blood seals the deal. SH can act coldly as she feels justified that B has died, the threat is out of her hands, and this joint act binds NM and SH irrevocably together, also motive is to keep them together so she will do anything.
