In Infinispan 9.1 we have made considerable changes to how partition handling is performed and introduced ConflictResolution . I advise that if possible you migrate to Infinispan 9.1.x and make use of a custom EntryMergePolicy implementation in order to resolve conflicts during a partition merge. Note, this is only available if you utilise the ALLOW_READ_WRITES partition strategy, which is analogous to setting partition handling to disabled in 8.2.6.
I'm able to find in official documentation for 8.2.6 how system behaves when your replicated or distributed caches has configured <partition-handling enabled="true"/>. Is there available some documentation also, how in 8.2.6 caches/split brain problem/conflict resolution behaves for this version?