The Seria file is similar to the INI file for its key-value pair format and the JSON file for its curly bracket pairs. This makes it a hierarchical structure.
Some key points we can observe from the file:

• The file can have nested bracket pairs inside another bracket pair
  
• The content inside a bracket pair always starts with the m_classname attribute.

With this in mind, we can start analysing the composition of the profile and understand the purpose of each part of the profile.
Some terminology notice: because the Seria file has a tree-like structure, I will refer to each section as a node for convenience. For example, Profile is the root node and Escadra is a direct child node of the Profile node. However, it is also worth noticing that the Seria file has a m_classname named exactly Node. Care needs to be taken to distinguish between the meanings of the two.

Above is a typical profile structure in the middle of the campaign. [...] denotes a series of the same node as the previous one, they are being omitted here because there are dozens, hundreds of them.

Escadra, as the name suggests, contains information about the ships on the map. This includes transport, strike group and player's fleet.

Location contains information about the city on the map, this includes callsign, city type (e.g. Fuel Depot), parts and ammunition sold by the city.

NPC contains information about all hireable characters in the game. Besides, all purchasable ships in a city are technically owned by an NPC (so they also have their own NPC node and if you take a close look, each NPC even has its own name and characteristic such as force and kindness).

There are a few Item nodes that are directly stored as a child node of the root profile node. From what we know so far, these nodes contain information about the player's ammunition depot (because all ships can access it whether they are in a detachment or not, this is less related to a specific location or an escadra, I figure that's why it stores at the bottom of the profile).

The last Node node (yes, its just named Node). Contains information about the paint mark (e.g. pencil marker and ruler) the player put on the map. Sometimes it's also being used to store inventory parts (I am not too sure about this, because the position where inventory parts can change between city or in-air fleet, need further verification)

Above is a more detailed look at the Escadra node. The first node details the design of the ship. There are also intels that relate to the ship if it is an enemy ship or intercepted by a player ship. Escadra::MapShip is a node that details the ship's position on the strategic map.

The last Node node within an Escadra node stores the information about the inventory parts of the fleet. Because we know that when a detachment acquires a part, that part will stay with the detachment before it is returned to the flagship. As a result, the parts are technically stored in individual ships. There are several Body nodes that lie within the Node node. Each Body node defines a type of part stored in that fleet (e.g. missile), its quantity and which ship's inventory it belongs to (this is crucial for inventory modification).

Based on this information, it is technically possible for us to add or delete parts from a ship's inventory. Allowing real parts allocation possible, so that a detachment can get some missile supply from the flagship or simply cheat for any number of parts you want.

Above is a typical composition of a Location node. The first series of Item node contains information about ammunition sold in the supplies. Each Item node represent a type of ammunition. The last Node node contains information about each parts sold in the shipyard. Each Body node within the Node node represent a type of parts. This is similar to the ship's inventory.

Since we know that the last series of Item nodes is about player's ammunition. The modification is easy: just scroll down to the end of the profile. Identify which type of ammunition you want to change. Refer to the example above, m_index defines the type of ammunition and m_count is the quantity of that ammunition.

The easiest way to identify an Node (inventory) node is to look for the Escadra::MapShip node. Open a file editor and press ctrl+f key to use the search function. The Escadra::MapShip node also contains useful attributes such as pEscadra.id to help you identify which ship this inventory belongs to. Since directly scrolling up is quite challenging. The outer Node node has a m_id attribute which is unique to each inventory. If you look at the Body node for the BOMB in this example, you will find out that there is a m_master_id that points to this inventory id.

When you copy/create parts to another inventory, you need to change these attributes accordingly to match the target inventory. Not doing so will cause the game to crash. So, be careful and remember to back up your file!

Another attribute that is worth noticing is the m_count attribute which defines the quantity of this part. And imagine having hundreds of missiles. We will bring peace to the Gerat (lol).