diff --git a/LibCmo/CK2/CKContext.cpp b/LibCmo/CK2/CKContext.cpp
index ab9244a..ad9751c 100644
--- a/LibCmo/CK2/CKContext.cpp
+++ b/LibCmo/CK2/CKContext.cpp
@@ -93,10 +93,47 @@ namespace LibCmo::CK2 {
 
 #pragma endregion
 
+#pragma region Common Manager Functions
+	
+	CKINT CKContext::GetManagerCount() {
+		return 0;
+	}
+
+	MgrImpls::CKBaseManager* CKContext::GetManager(int index) {
+		return nullptr;
+	}
+
+#pragma endregion
+
+#pragma region File Save/Load Options
+
+	void CKContext::SetCompressionLevel(CKINT level) {
+		if (level > 0 && level < 10) {
+			m_CompressionLevel = level;
+		}
+	}
+
+	CKINT CKContext::GetCompressionLevel() {
+		return m_CompressionLevel;
+	}
+
+	void CKContext::SetFileWriteMode(CK_FILE_WRITEMODE mode) {
+		m_FileWriteMode = mode;
+	}
+
+	CK_FILE_WRITEMODE CKContext::GetFileWriteMode() {
+		return m_FileWriteMode;
+	}
+
+
+#pragma endregion
+
+
 #pragma region Ctor Dtor
 
 	CKContext::CKContext() :
 		m_ObjectsList(), m_ReturnedObjectIds(),
+		m_CompressionLevel(5), m_FileWriteMode(CK_FILE_WRITEMODE::CKFILE_UNCOMPRESSED),
 		m_NameEncoding(), m_TempFolder(),
 		m_OutputCallback(nullptr)
 	{
diff --git a/LibCmo/CK2/CKContext.hpp b/LibCmo/CK2/CKContext.hpp
index ba3bc9c..af932a9 100644
--- a/LibCmo/CK2/CKContext.hpp
+++ b/LibCmo/CK2/CKContext.hpp
@@ -57,6 +57,19 @@ namespace LibCmo::CK2 {
 		//CKINT GetObjectsCountByClassID(CK_CLASSID cid);
 		//CK_ID* GetObjectsListByClassID(CK_CLASSID cid);
 
+		// ========== Common Managers Functions ==========
+
+		CKINT GetManagerCount();
+		MgrImpls::CKBaseManager* GetManager(int index);
+
+		// ========== File Save/Load Options ==========
+		
+		void SetCompressionLevel(CKINT level);
+		CKINT GetCompressionLevel();
+
+		void SetFileWriteMode(CK_FILE_WRITEMODE mode);
+		CK_FILE_WRITEMODE GetFileWriteMode();
+
 		// ========== Encoding utilities ==========
 
 		void GetUtf8String(const std::string& native_name, std::string& u8_name);
@@ -81,6 +94,10 @@ namespace LibCmo::CK2 {
 		XContainer::XArray<ObjImpls::CKObject*> m_ObjectsList;
 		std::deque<CK_ID> m_ReturnedObjectIds;
 
+		// ========== File Save/Load Options ==========
+		CKINT m_CompressionLevel;
+		CK_FILE_WRITEMODE m_FileWriteMode;
+
 		// ========== Encoding utilities ==========
 
 		std::vector<EncodingHelper::ENCODING_TOKEN> m_NameEncoding;
diff --git a/LibCmo/CK2/CKFile.hpp b/LibCmo/CK2/CKFile.hpp
index eb0bcda..d8ea959 100644
--- a/LibCmo/CK2/CKFile.hpp
+++ b/LibCmo/CK2/CKFile.hpp
@@ -17,12 +17,26 @@ namespace LibCmo::CK2 {
 		size_t m_MemSize;
 
 	public:
+		/**
+		 * @brief Create CKBufferParser from a existed buffer.
+		 * @param ptr The start pointer of buffer. This buffer should be allocated by 'new[]', not 'new' or 'malloc()'.
+		 * @param rsize The size of buffer.
+		 * @param need_manual_free True if provided buffer need freed by CKBufferParser automatically.
+		*/
 		CKBufferParser(void* ptr, size_t rsize, bool need_manual_free) :
 			m_MemBegin(static_cast<char*>(ptr)),
 			m_MemPos(0u), m_MemSize(rsize),
-			m_NeedManualFree(need_manual_free) {
-			;
-		}
+			m_NeedManualFree(need_manual_free) 
+		{}
+		/**
+		 * @brief Create CKBufferParser from a new created buffer.
+		 * @param newsize The size of new buffer.
+		*/
+		CKBufferParser(size_t newsize) :
+			m_MemBegin(new char[newsize]),
+			m_MemPos(0u), m_MemSize(newsize),
+			m_NeedManualFree(true)
+		{}
 		~CKBufferParser() {
 			if (this->m_NeedManualFree) delete[](this->m_MemBegin);
 		}
@@ -209,6 +223,22 @@ namespace LibCmo::CK2 {
 		CKERROR Save(CKSTRING u8_filename);
 
 	protected:
+		CKBOOL m_Done;
+		/**
+		 * True if this writer is copy from reader.
+		 * The data copied from reader mean that calling just only do some small modification.
+		 * So we don't need try getting some managers or save file options from CKContext.
+		 * Just apply the data coming from reader.
+		 * Also, Add object functions is not allowed when writer copying from reader. 
+		*/
+		CKBOOL m_IsCopyFromReader;
+		
+		XContainer::XArray<CKFileObject> m_FileObjects; /**< List of objects being saved / loaded */
+		XContainer::XArray<CKFileManagerData> m_ManagersData; /**< Manager Data loaded */
+		XContainer::XArray<CKFilePluginDependencies> m_PluginsDep;	/**< Plugins dependencies for this file */
+		XContainer::XArray<XContainer::XString> m_IncludedFiles; /**< List of files that should be inserted in the CMO file. */
+		CKFileInfo m_FileInfo; /**< Headers summary */
+
 		CKContext* m_Ctx;
 		CKFileVisitor m_Visitor;
 	};
diff --git a/LibCmo/CK2/CKFileOthers.cpp b/LibCmo/CK2/CKFileOthers.cpp
index 14a34dc..b0bcc22 100644
--- a/LibCmo/CK2/CKFileOthers.cpp
+++ b/LibCmo/CK2/CKFileOthers.cpp
@@ -13,12 +13,12 @@ namespace LibCmo::CK2 {
 	CKFileObject::CKFileObject() :
 		ObjectId(0u), CreatedObjectId(0u), ObjectCid(CK_CLASSID::CKCID_OBJECT),
 		ObjPtr(nullptr), Name(), Data(nullptr), Options(CK_FO_OPTIONS::CK_FO_DEFAULT),
-		FileIndex(0u), SaveFlags(0u) {}
+		FileIndex(0u), SaveFlags(CK_STATESAVE_ALL) {}
 
 	CKFileObject::CKFileObject(const CKFileObject& rhs) :
 		ObjectId(rhs.ObjectId), CreatedObjectId(rhs.CreatedObjectId), ObjectCid(rhs.ObjectCid),
 		ObjPtr(rhs.ObjPtr), Name(rhs.Name), Data(rhs.Data), Options(rhs.Options),
-		FileIndex(rhs.FileIndex), SaveFlags(0u) {
+		FileIndex(rhs.FileIndex), SaveFlags(rhs.SaveFlags) {
 		if (this->Data != nullptr) {
 			this->Data = new CKStateChunk(*(rhs.Data));
 		}
@@ -27,7 +27,7 @@ namespace LibCmo::CK2 {
 	CKFileObject::CKFileObject(CKFileObject&& rhs) :
 		ObjectId(rhs.ObjectId), CreatedObjectId(rhs.CreatedObjectId), ObjectCid(rhs.ObjectCid),
 		ObjPtr(rhs.ObjPtr), Name(rhs.Name), Data(rhs.Data), Options(rhs.Options),
-		FileIndex(rhs.FileIndex), SaveFlags(0u) {
+		FileIndex(rhs.FileIndex), SaveFlags(rhs.SaveFlags) {
 		rhs.Data = nullptr;
 	}
 
@@ -158,22 +158,81 @@ namespace LibCmo::CK2 {
 #pragma region CKFileWriter
 
 	CKFileWriter::CKFileWriter(CKContext* ctx) :
-		m_Ctx(ctx), m_Visitor(this) {}
+		m_Ctx(ctx), m_Visitor(this),
+		m_Done(false), m_IsCopyFromReader(false),
+		m_FileObjects(), m_ManagersData(), m_PluginsDep(), m_IncludedFiles(),
+		m_FileInfo()
+	{}
 
 	CKFileWriter::CKFileWriter(CKContext* ctx, CKFileReader* reader) :
-		m_Ctx(ctx), m_Visitor(this) {}
+		m_Ctx(ctx), m_Visitor(this),
+		m_Done(false), m_IsCopyFromReader(true),
+		m_FileObjects(), m_ManagersData(), m_PluginsDep(), m_IncludedFiles(),
+		m_FileInfo()
+	{
+		// copy objects
+		for (const auto& item : reader->GetFileObjects()) {
+			CKFileObject obj;
+			// copy CKObject pointer
+			obj.ObjPtr = item.ObjPtr;
+			// and use ctor to copy CKStateChunk
+			if (item.Data == nullptr) {
+				obj.Data = nullptr;
+			} else {
+				obj.Data = new CKStateChunk(*item.Data);
+			}
+
+			// copy save flag
+			obj.SaveFlags = item.SaveFlags;
+
+			// insert
+			m_FileObjects.emplace_back(std::move(obj));
+		}
+
+		// copy managers
+		for (const auto& item : reader->GetManagersData()) {
+			CKFileManagerData mgr;
+			// copy guid
+			mgr.Manager = item.Manager;
+			// copy chunk
+			if (item.Data == nullptr) {
+				mgr.Data = nullptr;
+			} else {
+				mgr.Data = new CKStateChunk(*item.Data);
+			}
+
+			// insert
+			m_ManagersData.emplace_back(std::move(mgr));
+		}
+
+		// copy plugin dep
+		for (const auto& item : reader->GetPluginsDep()) {
+			// direct copy
+			m_PluginsDep.emplace_back(item);
+		}
+
+		// copy included file
+		for (const auto& item : reader->GetIncludedFiles()) {
+			// direct copy
+			m_IncludedFiles.emplace_back(item);
+		}
+
+	}
 
 	CKFileWriter::~CKFileWriter() {}
 
 	CKBOOL CKFileWriter::AddSavedObject(ObjImpls::CKObject* obj, CKDWORD flags) {
+		if (m_Done || m_IsCopyFromReader) return CKFALSE;
 		return CKFALSE;
 	}
 
 	CKBOOL CKFileWriter::AddSavedObjects(CKObjectArray* objarray, CKDWORD flags) {
+		if (m_Done || m_IsCopyFromReader) return CKFALSE;
 		return CKFALSE;
 	}
 
 	CKBOOL CKFileWriter::AddSavedFile(CKSTRING u8FileName) {
+		if (m_Done || m_IsCopyFromReader) return CKFALSE;
 		return CKFALSE;
 	}
 
diff --git a/LibCmo/CK2/CKGlobals.cpp b/LibCmo/CK2/CKGlobals.cpp
index 7086e49..87409de 100644
--- a/LibCmo/CK2/CKGlobals.cpp
+++ b/LibCmo/CK2/CKGlobals.cpp
@@ -155,11 +155,12 @@ namespace LibCmo::CK2 {
 
 	CKBOOL CKIsChildClassOf(CK_CLASSID child, CK_CLASSID parent) {
 		// get corresponding index first
+		// if we can't find it, return false anyway.
 		auto finder = g_CKClassInfoId2Idx.find(child);
-		if (finder == g_CKClassInfoId2Idx.end()) LIBPANIC("No such CK_CLASSID.");
+		if (finder == g_CKClassInfoId2Idx.end()) return CKFALSE;
 		size_t child_idx = finder->second;
 		finder = g_CKClassInfoId2Idx.find(parent);
-		if (finder == g_CKClassInfoId2Idx.end()) LIBPANIC("No such CK_CLASSID.");
+		if (finder == g_CKClassInfoId2Idx.end()) return CKFALSE;
 		size_t parent_idx = finder->second;
 
 		return g_CKClassInfo[child_idx].Parents[parent_idx];
diff --git a/LibCmo/VTUtils.hpp b/LibCmo/VTUtils.hpp
index 86b12ae..d750cbf 100644
--- a/LibCmo/VTUtils.hpp
+++ b/LibCmo/VTUtils.hpp
@@ -119,6 +119,11 @@ namespace LibCmo {
 			const char* c_str() const {
 				return m_HasStr ? m_Str.c_str() : nullptr;
 			}
+
+			const size_t size() const {
+				return m_HasStr ? m_Str.size() : 0u;
+			}
+
 		private:
 			bool m_HasStr;
 			std::string m_Str;