each delta has .with and LikeWith to find X related to Y

src/ledger/transaction.go

@@ -165,6 +165,15 @@ func (t transaction) deltas() Deltas {
 			))
 		}
 	}
+
+	for i := range result {
+		for j := range result {
+			if i != j {
+				result[i] = result[i].withWith(result[j])
+			}
+		}
+	}
+
 	return result
 }