> ## Documentation Index
> Fetch the complete documentation index at: https://docs.xbox.com/llms.txt
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# XblMultiplayerSessionAddMemberReservation

> XblMultiplayerSessionAddMemberReservation

Add a new member reservation on the session for the specified xuid and member constants.

## Syntax

```cpp theme={null}
HRESULT XblMultiplayerSessionAddMemberReservation(  
         XblMultiplayerSessionHandle handle,  
         uint64_t xuid,  
         const char* memberCustomConstantsJson,  
         bool initializeRequested  
)  
```

### Parameters

*handle*   \_In\_\
Type: [XblMultiplayerSessionHandle](https://docs.xbox.com/reference/live/xsapi-c/multiplayer_c/handles/xblmultiplayersessionhandle.md)

Handle to the multiplayer session.

*xuid*   \_In\_\
Type: uint64\_t

The xuid to add a reservation for.

*memberCustomConstantsJson*   \_In\_opt\_z\_\
Type: char\*

The custom constants to set for this member. This is the only time the member's constants can be set. (Optional)

*initializeRequested*   \_In\_\
Type: bool

True if the system should perform managed initialization, and false otherwise.

### Return value

Type: HRESULT

HRESULT return code for this API operation.

## Requirements

**Header:** multiplayer\_c.h

**Library:** Microsoft.Xbox.Services.142.C.lib or Microsoft.Xbox.Services.143.C.lib

## See also

[multiplayer\_c](https://docs.xbox.com/reference/live/xsapi-c/multiplayer_c/multiplayer_c_members.md)


## Related topics

- [XblMultiplayerSessionMembers](https://docs.xbox.com/reference/live/xsapi-c/multiplayer_c/functions/xblmultiplayersessionmembers.md)
- [XblMultiplayerSessionCurrentUserSetStatus](https://docs.xbox.com/reference/live/xsapi-c/multiplayer_c/functions/xblmultiplayersessioncurrentusersetstatus.md)
- [Multiplayer FAQ and troubleshooting](https://docs.xbox.com/services/xbox-services/multiplayer/mpsd/concepts/live-multiplayer-2015-faq.md)
- [Game session visibility and joinability](https://docs.xbox.com/services/xbox-services/multiplayer/mpsd/concepts/live-game-session-visibility-joinability.md)
- [multiplayer_c (contents)](https://docs.xbox.com/reference/live/xsapi-c/multiplayer_c/multiplayer_c_members.md)