Imagine a shrub made of shrub A and shrub B. Parts of the shrub (from the root) are from both, parts are from A only, and parts are from B only. Imagine also th

Imagine a shrub made of shrub A and shrub B. Parts of the shrub (from the root) are from both, parts are from A only, and parts are from B only. Imagine also the 2 sets of labels from A and B. It would become clear how the push/pull is updating its target shrub, and indeed if and what bits of the 2 shrubs (or their labels) conflict.