diff --git a/pasch/file/json.py b/pasch/file/json.py
index 2dd32d6..b09b4a5 100644
--- a/pasch/file/json.py
+++ b/pasch/file/json.py
@@ -1,12 +1,28 @@
-from typing import Self
 import json
 from dataclasses import dataclass
-from typing import Any
+from typing import Any, Self
 
 from .file import TAG, File
 from .text import TextFile
 
 
+def _merge_values(a: Any, b: Any) -> Any:
+    if not isinstance(a, dict) or not isinstance(b, dict):
+        return b
+
+    result = {}
+    for k, v_a in a.items():
+        result[k] = v_a
+    for k, v_b in b.items():
+        v_a = a.get(k)
+        if v_a is None:
+            result[k] = v_b
+        else:
+            result[k] = _merge_values(v_a, v_b)
+
+    return result
+
+
 @dataclass
 class JsonFileProxy:
     file: "JsonFile"
@@ -15,18 +31,14 @@ class JsonFileProxy:
     def at(self, *path: str) -> Self:
         return JsonFileProxy(self.file, self.path + path)
 
-    def set(self, value: Any) -> None:
-        if not self.path:
-            self.file.set(value)
+    def set(self, path: str | tuple[str, ...], value: Any) -> None:
+        if isinstance(path, str):
+            path = (path,)
 
-        data = self.file.data
-        *parts, last = self.path
-        for part in parts:
-            data = data.setdefault(part, {})
-        data[last] = value
+        self.file.set(self.path + path, value)
 
-    def tag_here(self, tag: str = TAG) -> None:
-        self.set(tag)
+    def tag(self, path: str | tuple[str, ...] = "_tag") -> None:
+        self.set(path, TAG)
 
 
 class JsonFile(File):
@@ -36,13 +48,32 @@ class JsonFile(File):
     def at(self, *path: str) -> JsonFileProxy:
         return JsonFileProxy(self, path)
 
-    def set(self, value: Any) -> None:
-        self.data = value
+    def get(self, path: str | tuple[str, ...]) -> Any:
+        data = self.data
+        for part in path:
+            data = data[part]
+        return data
 
-    def tag(self, tag: str = TAG, key: str | list[str] = "_tag") -> None:
-        if isinstance(key, str):
-            self.at(key).tag_here(tag=tag)
-        self.at(*key).tag_here(tag=tag)
+    def set(self, path: str | tuple[str, ...], value: Any) -> None:
+        if isinstance(path, str):
+            path = (path,)
+
+        if not path:
+            self.data = value
+            return
+
+        *parts, last = path
+
+        data = self.data
+        for part in parts:
+            data = data.setdefault(part, {})
+        data[last] = value
+
+    def merge(self, path: str | tuple[str, ...], value: Any) -> None:
+        self.set(path, _merge_values(self.get(path), value))
+
+    def tag(self, path: str | tuple[str, ...] = "_tag") -> None:
+        self.set(path, TAG)
 
     def to_text(self) -> TextFile:
         return TextFile(json.dumps(self.data))
diff --git a/pasch/file/toml.py b/pasch/file/toml.py
index 688ffed..6005901 100644
--- a/pasch/file/toml.py
+++ b/pasch/file/toml.py
@@ -4,6 +4,7 @@ from typing import Any, Self
 import toml
 
 from .file import File
+from .json import JsonFile
 from .text import TextFile
 
 
@@ -15,31 +16,33 @@ class TomlFileProxy:
     def at(self, *path: str) -> Self:
         return TomlFileProxy(self.file, self.path + path)
 
-    def set(self, value: Any) -> None:
-        if not self.path:
-            self.file.set(value)
+    def set(self, path: str | tuple[str, ...], value: Any) -> None:
+        if isinstance(path, str):
+            path = (path,)
 
-        data = self.file.data
-        *parts, last = self.path
-        for part in parts:
-            data = data.setdefault(part, {})
-        data[last] = value
+        self.file.set(self.path + path, value)
 
 
 class TomlFile(File):
     def __init__(self, data: Any = {}) -> None:
-        self.data = data
+        self.json = JsonFile(data)
 
     def at(self, *path: str) -> TomlFileProxy:
         return TomlFileProxy(self, path)
 
-    def set(self, value: Any) -> None:
-        self.data = value
+    def get(self, path: str | tuple[str, ...]) -> Any:
+        return self.json.get(path)
+
+    def set(self, path: str | tuple[str, ...], value: Any) -> None:
+        self.json.set(path, value)
+
+    def merge(self, path: str | tuple[str, ...], value: Any) -> None:
+        self.json.merge(path, value)
 
     def to_text(self) -> TextFile:
         file = TextFile()
         file.tag(comment="#")
-        file.append(toml.dumps(self.data), newline=False)
+        file.append(toml.dumps(self.json.data), newline=False)
         return file
 
     def to_bytes(self) -> bytes: