# CF3 Interaction Authority — UE5 Multiplayer Interaction System with Late-Join Proof 

**URL:** <https://forums.unrealengine.com/t/cf3-interaction-authority-ue5-multiplayer-interaction-system-with-late-join-proof/2719307>\
**Category:** Publisher Announcements & Product Help\
**Tags:** Replication, unreal-engine, plugin, Multiplayer, fab\
**Created:** [April 30, 2026, 11:39pm UTC](https://forums.unrealengine.com/t/cf3-interaction-authority-ue5-multiplayer-interaction-system-with-late-join-proof/2719307 "2026-04-30T23:39:21Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Stark3y933](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Stark3y933](https://forums.unrealengine.com/u/Stark3y933)\
**Post date:** [April 30, 2026, 11:39pm UTC](https://forums.unrealengine.com/t/cf3-interaction-authority-ue5-multiplayer-interaction-system-with-late-join-proof/2719307/1 "2026-04-30T23:39:21Z")

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Hi everyone,

**This is CF3 Systems**.

I’ve released [CF3 Interaction Authority](https://fab.com/s/1db10dd878fe), a UE5 multiplayer interaction system focused on server authoritative validation, replicated state, and late-join-safe interaction examples.

**The goal is to solve a common multiplayer problem** :

client sends interaction intent

server validates the target

server applies the result

replicated state rebuilds correctly for other clients and late joiners

**Included demo examples** :

replicated door interaction

replicated pickup interaction

persistent button interaction

momentary button interaction

optional interaction prompt UI

range and line-of-sight validation

The system is designed so the authority logic stays separate from the demo UI and player setup.

Proof video:

[![](https://d3kjluh73b9h9o.cloudfront.net/original/4X/d/3/a/d3af201f754caf6593c3b5aaea1ec38d06e99834.jpeg "UE5 Interaction System for Multiplayer | Replicated, Late-Join Safe") ](https://www.youtube.com/watch?v=ARZvx9ybmno)

Fab product page:

> **[UE5 Interaction System for Multiplayer (Replicated, No Desync)](https://www.fab.com/listings/9d0b9530-8fb7-419b-8860-a44c56a7038a)**
>
> Multiplayer Proof Video:https://youtube/ARZvx9ybmnoDocumentation Included:A professional PDF guide is included with the listing. It covers setup, usage notes, multiplayer interaction flow, door/pickup/button examples, replication behavior, late-join...

Documentation:

> **[CF3\_Interaction\_Authority\_Professional\_Guide.pdf](https://drive.google.com/file/d/1UBRjaQHL_Fpvuu0GI49_tl14Cl42y_c9/view?usp=sharing)**
>
> Google Drive file.

This thread is for product questions, setup help, feedback, and future update notes.

Feedback on the proof video, documentation, or multiplayer setup flow would be appreciated.