Questions: Nexus Sprint Backlog

1. Potentially either. It's the composite of the Nexus Sprint Goal and PBIs from the Sprint Backlogs of the individual Scrum Teams. What matters is that it highlights any dependencies and reveals the flow of work during the Sprint.

2. Why would their evolution need to be staged at all?

3, 4. The Nexus Guide says that the Nexus Sprint Backlog represents the work of the Nexus. It's theirs. No one else would own or manage it.

Thanks Ian for the response.

Q1: If it is either, in that case i would follow what The Nexus Framework for Scaling Scrum book has clearly mentioned 'Only PBI's those have dependencies across Scrum Teams'.

Q2: 2021 Nexus Guide says 'A Nexus Sprint Backlog is the composite of the Nexus Sprint Goal and Product Backlog items from the Sprint Backlog of Individual Scrum teams.'. The word 'from' make it sound like Nexus Sprint backlog items are 'coming from' Sprint Backlog of Individual Scrum teams or 'inducted after' Sprint Backlog of Individual Scrum teams. Although the framework diagram in The Nexus Guide doesn't show where it sits (including 2018 version of Nexus Guide where the other Scrum components were shown exactly where it appears in the Nexus flow).

Q3/4: I understand Nexus Sprint Backlog (NSB) belongs to Nexus, but unlike simple Scrum where we have 1 team responsible for everything, in Nexus we have 3-9 Scrum Teams, thus the definition or the word 'their' become too wide to pinpoint who/ which team, specially in the case when each team has their own Sprint Backlog to manage. Although NIT is NOT responsible for delivery of integration but they are still accountable for all the integration work. Thus the Ownership of the NSB logically fall with NIT but the Management of NSB could be either with the Scrum team or NIT. But nothing is clearly written either in Nexus Guide or The Nexus Framework for Scaling Scrum book.

Please share your views on my understanding of Q2/3/4.

The NSB is a composite of each teams SB; however, dependencies are identified first and then added to the NSB & SB possibly at the same time (SB might be a bit later as the PBIs have to be chosen by the teams before going into their SB).  

The NIT updates the NSB as part of their NDS at a minimum (remember that dependencies should be reported immediately once they have been identified).  

Major point to remember is that the NIT is made up from members of each team that meet the appropriate criteria for that specific Nexus event in time, meaning that the team members can be different for each event instance.