diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/Justified.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/Justified.kt
index adb1011f..ff74d977 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/Justified.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/Justified.kt
@@ -66,6 +66,11 @@ interface Justified {
      */
     fun justifiedByAny(others: Collection<Justified>): Boolean =
         others.any { this.justifiedBy(it) }
+
+    /**
+     * Append [Justifications] from [other] entity to justifications of this [Justified]
+     */
+    fun justifyBy(other: Justified): Unit { justifications().addAll(other.justifications()) }
 }
 
 
diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/ControllerImpl.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/ControllerImpl.kt
index f1cc0c1a..be45fba9 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/ControllerImpl.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/ControllerImpl.kt
@@ -165,7 +165,9 @@ internal class ControllerImpl (
                 //  then they must be tracked somewhere above --- i.e. in its parent
                 match.allHeads().filter { it.isPrincipal() && !it.justifiedBy(parent) }.forEach {
                     // Avoid justifying parent by its child!
-                    parent.justifyBy(it)
+                    processing.forEachChunkFrom(parent.toPos()) { child ->
+                        child.justifyBy(it)
+                    }
                 }
             }
 
@@ -239,6 +241,7 @@ internal class ControllerImpl (
 
             profiler.profile<FeedbackStatus>("activate_${constraint.symbol()}") {
 
+                // fixme: maybe provide no evidence for non-principal constraints?
                 constraint.occurrence(logicalStateObservable(), args, processing.nextEvidence(), justifications, context.logicalContext, context.ruleUniqueTag).let { occ ->
                     trace.activate(occ)
                     processing.processActivated(this, occ, parent, status)
diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/MatchJournal.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/MatchJournal.kt
index a72a6f0c..51564a58 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/MatchJournal.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/MatchJournal.kt
@@ -88,6 +88,13 @@ interface MatchJournal : MutableIterable<MatchJournal.Chunk>, EvidenceSource {
      */
     fun replay(observable: LogicalStateObservable, futurePos: Pos)
 
+    /**
+     * Walk from specified [from] position in journal until current position
+     * while applying [action] to each visited [Chunk].
+     * Occurrences are accordingly reset and replayed
+     */
+    fun forEachChunkFrom(from: Pos, action: (Chunk) -> Unit)
+
     /**
      * Returns snapshot of the journal.
      */
@@ -167,8 +174,6 @@ interface MatchJournal : MutableIterable<MatchJournal.Chunk>, EvidenceSource {
     class MatchChunk(override val evidence: Evidence, val match: RuleMatch) : Chunk {
         private val justifications = match.justifications().apply { add(evidence) }
 
-        fun justifyBy(other: Justified): Unit { justifications.addAll(other.justifications()) }
-
         override fun justifications(): Justifications = justifications
 
         override var entries: MutableList<Chunk.Entry> = mutableListOf()
diff --git a/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/MatchJournalImpl.kt b/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/MatchJournalImpl.kt
index 1ec9302d..cc7adca8 100644
--- a/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/MatchJournalImpl.kt
+++ b/reactor/Core/src/jetbrains/mps/logic/reactor/core/internal/MatchJournalImpl.kt
@@ -148,6 +148,12 @@ internal open class MatchJournalImpl(
         if (currentPos() != pastPos) throw IllegalStateException()
     }
 
+    override fun forEachChunkFrom(from: Pos, action: (Chunk) -> Unit) {
+        val to = currentPos()
+        resetPos(from, false)
+        replayWith(to, action)
+    }
+
     override fun replay(observable: LogicalStateObservable, futurePos: MatchJournal.Pos) = replayWith(futurePos, {})
 
     private fun replayWith(futurePos: MatchJournal.Pos, action: (Chunk) -> Unit) {