diff --git a/simulation-kt/src/commonMain/kotlin/GeneratingTimeline.kt b/simulation-kt/src/commonMain/kotlin/GeneratingTimeline.kt
index 5690d7c..0698b45 100644
--- a/simulation-kt/src/commonMain/kotlin/GeneratingTimeline.kt
+++ b/simulation-kt/src/commonMain/kotlin/GeneratingTimeline.kt
@@ -22,11 +22,11 @@ public fun <E : TimelineEvent> Flow<E>.withTimeThreshold(
  * @param lookaheadInterval an interval for generated events ahead of the last observed event.
  */
 public class GeneratingTimeline<E : TimelineEvent>(
-    private val origin: E,
+    origin: E,
     private val lookaheadInterval: Duration,
     coroutineContext: CoroutineContext = EmptyCoroutineContext,
     private val generator: suspend FlowCollector<E>.(E) -> Unit
-) : AbstractTimeline<E>(origin.time, coroutineContext) {
+) : ProducerTimeline<E>(origin.time, coroutineContext) {
 
     private val startEventFlow = MutableStateFlow(origin)
 
diff --git a/simulation-kt/src/commonMain/kotlin/MergedTimeline.kt b/simulation-kt/src/commonMain/kotlin/MergedTimeline.kt
index 0da6227..4614fbb 100644
--- a/simulation-kt/src/commonMain/kotlin/MergedTimeline.kt
+++ b/simulation-kt/src/commonMain/kotlin/MergedTimeline.kt
@@ -1,7 +1,11 @@
 package space.kscience.simulation
 
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.*
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import kotlinx.datetime.Instant
 import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.EmptyCoroutineContext
 
@@ -9,18 +13,70 @@ import kotlin.coroutines.EmptyCoroutineContext
 public class MergedTimeline<E : TimelineEvent>(
     private val timelines: List<Timeline<E>>,
     coroutineContext: CoroutineContext = EmptyCoroutineContext
-) : AbstractTimeline<E>(timelines.minOf { it.time.value }, coroutineContext) {
+) : Timeline<E> {
 
-    override fun events(): Flow<E> = flow {
-        val buffer = TODO()
-//
-//        timelines.forEach { timeline ->
-//            timeline.observe {
-//                collect{
-//                    buffer.add(it)
-//                }
-//            }
-//        }
+    protected val timelineScope: CoroutineScope = CoroutineScope(
+        coroutineContext +
+                SupervisorJob(coroutineContext[Job]) +
+                CoroutineExceptionHandler{ _, throwable -> throwable.printStackTrace() } +
+                CoroutineName("MergedTimeline")
+    )
+
+    override val time: StateFlow<Instant> = combine(timelines.map { it.time }){ array->
+        array.max()
+    }.stateIn(timelineScope, SharingStarted.Lazily, timelines.maxOf { it.time.value })
+
+    override suspend fun advance(toTime: Instant) {
+        observers.forEach {
+            it.collect(toTime)
+        }
+    }
+
+    private val observers: MutableSet<TimelineObserver> = mutableSetOf()
+
+    override suspend fun observe(collector: suspend Flow<E>.() -> Unit): TimelineObserver {
+        val context = currentCoroutineContext()
+        val buffer = mutableListOf<E>()
+
+        val timelineObservers = timelines.map {
+            it.observeEach { event ->
+                buffer.add(event)
+            }
+        }
+
+        val observer = object : TimelineObserver {
+
+            private val channel = Channel<E>()
+
+            override val time = MutableStateFlow(this@MergedTimeline.time.value)
+
+            private val collectJob = timelineScope.launch(context) {
+                channel.consumeAsFlow().onEach {
+                    time.emit(it.time)
+                }.collector()
+            }
+
+            private val mutex = Mutex()
+
+            override suspend fun collect(upTo: Instant) = mutex.withLock{
+                timelineObservers.forEach {
+                    it.collect(upTo)
+                }
+                buffer.sortedBy { it.time }.forEach {
+                    channel.send(it)
+                    buffer.remove(it)
+                }
+            }
+
+            override fun close() {
+                collectJob.cancel()
+                observers.remove(this)
+            }
+
+        }
+
+        observers.add(observer)
+        return observer
     }
 
 }
\ No newline at end of file
diff --git a/simulation-kt/src/commonMain/kotlin/AbstractTimeline.kt b/simulation-kt/src/commonMain/kotlin/ProducerTimeline.kt
similarity index 90%
rename from simulation-kt/src/commonMain/kotlin/AbstractTimeline.kt
rename to simulation-kt/src/commonMain/kotlin/ProducerTimeline.kt
index b4d243f..a201d92 100644
--- a/simulation-kt/src/commonMain/kotlin/AbstractTimeline.kt
+++ b/simulation-kt/src/commonMain/kotlin/ProducerTimeline.kt
@@ -4,10 +4,12 @@ import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.BufferOverflow
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
 import kotlinx.datetime.Instant
 import kotlin.coroutines.CoroutineContext
 
-public abstract class AbstractTimeline<E : TimelineEvent>(
+public abstract class ProducerTimeline<E : TimelineEvent>(
     protected var startTime: Instant,
     coroutineContext: CoroutineContext
 ) : Timeline<E>, AutoCloseable {
@@ -53,8 +55,9 @@ public abstract class AbstractTimeline<E : TimelineEvent>(
                 }.collector()
             }
 
+            private val mutex = Mutex()
 
-            override suspend fun collect(upTo: Instant) = coroutineScope {
+            override suspend fun collect(upTo: Instant) = mutex.withLock {
                 require(upTo >= time.value) { "Requested time $upTo is lower than observed ${time.value}" }
                 events().takeWhile {
                     it.time <= upTo
diff --git a/simulation-kt/src/commonMain/kotlin/SharedTimeline.kt b/simulation-kt/src/commonMain/kotlin/SharedTimeline.kt
index 1b45002..051524e 100644
--- a/simulation-kt/src/commonMain/kotlin/SharedTimeline.kt
+++ b/simulation-kt/src/commonMain/kotlin/SharedTimeline.kt
@@ -13,7 +13,7 @@ import kotlin.coroutines.EmptyCoroutineContext
 public class SharedTimeline<E : TimelineEvent>(
     startTime: Instant,
     coroutineContext: CoroutineContext = EmptyCoroutineContext
-) : AbstractTimeline<E>(startTime, coroutineContext) {
+) : ProducerTimeline<E>(startTime, coroutineContext) {
 
     private val events = MutableSharedFlow<E>(replay = Channel.UNLIMITED)