very first draft(to be worked on)

contracts/ChainIdManager.sol

@@ -12,7 +12,9 @@ contract ChainIdManager is Owned {
     // Fee to use up a Chain ID
     uint256 public immutable gasBurnAmount = 1000000;
 
-    constructor(uint64 _chainIdCounter) Owned() {chainIdCounter = _chainIdCounter;}
+    constructor(uint64 _chainIdCounter) Owned() {
+        chainIdCounter = _chainIdCounter;
+    }
 
     /**
      * @dev Adds a Chain ID to the deny list, this can be done if the chainId is used by another project
@@ -37,7 +39,7 @@ contract ChainIdManager is Owned {
      * @return chainId The next usable Chain ID
      */
     function getNextUsableChainId() public returns (uint64 chainId) {
-        // The burnGas function introduces a cost to use up chainIds. 
+        // The burnGas function introduces a cost to use up chainIds.
         // There are uint64(2**63=9.223372e+18) chainIds minus the publicly used chainIds available.
         // Using all of the chainIds would cost 9.223372e+18 * gasBurnAmount = 9.223372e+24 gas = 6.1489147e+17 blocks = 237226647377 years
         burnGas();
@@ -51,6 +53,6 @@ contract ChainIdManager is Owned {
     function burnGas() public view {
         uint256 counter = 0;
         uint256 _lowestLimit = gasleft() - gasBurnAmount;
-        while(gasleft() > _lowestLimit) counter++;
+        while (gasleft() > _lowestLimit) counter++;
     }
 }

contracts/ForkableBridge.sol

@@ -99,6 +99,22 @@ contract ForkableBridge is
         PolygonZkEVMBridge._setAndCheckClaimed(index);
     }
 
+    // @inheritdoc IForkableBridge
+    function createChild1() external onlyForkManger returns (address) {
+        // process all pending deposits/messages before coping over the state root.
+        updateGlobalExitRoot();
+        return _createChild1();
+    }
+
+    // @inheritdoc IForkableBridge
+    function createChild2(
+        address implementation
+    ) external onlyForkManger returns (address) {
+        // process all pending deposits/messages before coping over the state root.
+        updateGlobalExitRoot();
+        return _createChild2(implementation);
+    }
+
     // @inheritdoc IForkableBridge
     function createChildren(
         address implementation
@@ -200,7 +216,7 @@ contract ForkableBridge is
         public
         payable
         override(PolygonZkEVMBridge, IPolygonZkEVMBridge)
-        onlyBeforeForking
+        onlyBeforeCreatingChild1
     {
         PolygonZkEVMBridge.bridgeAsset(
             destinationNetwork,
@@ -222,7 +238,7 @@ contract ForkableBridge is
         payable
         virtual
         override(PolygonZkEVMBridge, IPolygonZkEVMBridge)
-        onlyBeforeForking
+        onlyBeforeCreatingChild1
     {
         PolygonZkEVMBridge.bridgeMessage(
             destinationNetwork,
@@ -246,7 +262,7 @@ contract ForkableBridge is
     )
         public
         override(IPolygonZkEVMBridge, PolygonZkEVMBridge)
-        onlyBeforeForking
+        onlyBeforeCreatingChild1
     {
         PolygonZkEVMBridge.claimMessage(
             smtProof,
@@ -276,7 +292,7 @@ contract ForkableBridge is
     )
         public
         override(IPolygonZkEVMBridge, PolygonZkEVMBridge)
-        onlyBeforeForking
+        onlyBeforeCreatingChild1
     {
         PolygonZkEVMBridge.claimAsset(
             smtProof,

contracts/ForkableGlobalExitRoot.sol

@@ -52,6 +52,21 @@ contract ForkableGlobalExitRoot is
         );
     }
 
+    /// @dev Public interface to create children. This can only be done by the forkmanager
+    /// @return The addresses of the two children
+    function createChild1() external onlyForkManger returns (address) {
+        return _createChild1();
+    }
+
+    /// @dev Public interface to create children. This can only be done by the forkmanager
+    /// @param implementation Allows to pass a different implementation contract for the second proxied child.
+    /// @return The addresses of the two children
+    function createChild2(
+        address implementation
+    ) external onlyForkManger returns (address) {
+        return _createChild2(implementation);
+    }
+
     /// @dev Public interface to create children. This can only be done by the forkmanager
     /// @param implementation Allows to pass a different implementation contract for the second proxied child.
     /// @return The addresses of the two children

contracts/ForkableZkEVM.sol

@@ -40,6 +40,18 @@ contract ForkableZkEVM is ForkableStructure, IForkableZkEVM, PolygonZkEVM {
         );
     }
 
+    // @inheritdoc IForkableZkEVM
+    function createChild1() external onlyForkManger returns (address) {
+        return _createChild1();
+    }
+
+    // @inheritdoc IForkableZkEVM
+    function createChild2(
+        address implementation
+    ) external onlyForkManger returns (address) {
+        return _createChild2(implementation);
+    }
+
     // @inheritdoc IForkableZkEVM
     function createChildren(
         address implementation
@@ -48,7 +60,7 @@ contract ForkableZkEVM is ForkableStructure, IForkableZkEVM, PolygonZkEVM {
     }
 
     ////////////////////////////////////////////////////////////////////////////
-    // For the following functions a modifier called: onlyBeforeForking is added.
+    // For the following functions a modifier called: onlyBeforeCreatingChild1 is added.
     // This ensure that the functions do not change the consolidated state after forking.
     ///////////////////////////////////////////////////////////////////////////
 
@@ -59,7 +71,7 @@ contract ForkableZkEVM is ForkableStructure, IForkableZkEVM, PolygonZkEVM {
         bytes32 newLocalExitRoot,
         bytes32 newStateRoot,
         bytes32[24] calldata proof
-    ) public override onlyBeforeForking {
+    ) public override onlyBeforeCreatingChild1 {
         PolygonZkEVM.verifyBatches(
             pendingStateNum,
             initNumBatch,
@@ -77,7 +89,7 @@ contract ForkableZkEVM is ForkableStructure, IForkableZkEVM, PolygonZkEVM {
         bytes32 newLocalExitRoot,
         bytes32 newStateRoot,
         bytes32[24] calldata proof
-    ) public override onlyBeforeForking {
+    ) public override onlyBeforeCreatingChild1 {
         PolygonZkEVM.verifyBatchesTrustedAggregator(
             pendingStateNum,
             initNumBatch,
@@ -90,7 +102,7 @@ contract ForkableZkEVM is ForkableStructure, IForkableZkEVM, PolygonZkEVM {
 
     function consolidatePendingState(
         uint64 pendingStateNum
-    ) public override onlyBeforeForking {
+    ) public override onlyBeforeCreatingChild1 {
         PolygonZkEVM.consolidatePendingState(pendingStateNum);
     }
 
@@ -102,7 +114,7 @@ contract ForkableZkEVM is ForkableStructure, IForkableZkEVM, PolygonZkEVM {
         bytes32 newLocalExitRoot,
         bytes32 newStateRoot,
         bytes32[24] calldata proof
-    ) public override onlyBeforeForking {
+    ) public override onlyBeforeCreatingChild1 {
         PolygonZkEVM.overridePendingState(
             initPendingStateNum,
             finalPendingStateNum,
@@ -119,7 +131,7 @@ contract ForkableZkEVM is ForkableStructure, IForkableZkEVM, PolygonZkEVM {
     function sequenceBatches(
         BatchData[] calldata batches,
         address l2Coinbase
-    ) public override onlyBeforeForking {
+    ) public override onlyBeforeCreatingChild1 {
         PolygonZkEVM.sequenceBatches(batches, l2Coinbase);
     }