Multiplayer - keeping a button in sync

Hey all

Just learning unreal networking so let me know if I am going about this the wrong way.

This is a simplified example but say I have a button that can have up to 2 people use it at any given time. So it has a list of who is using it. Each player also has a variable about which button they are currently using. This all gets assigned on the server and replicated over to the clients and that’s all working.

My issue is that I display a “Busy” notice when there are 2 people already in the list and you are looking at a button. What happens when a player stops using the button is their variable gets nulled and they are removed from the list. The client isnt seeing these updates on the same frame. They see their button variable get cleared so I show the Busy notice for a few frames before the list on the button gets updated to go back down to 1. So you see a flicker.

What are peoare strategies for dealing with stuff like this where you have 2 separate locations that need to stay synced at the same time.

Second question: if a bunch of updates happen on the same frame on the server, will clients see those all come together or is it possible those updates will trickle in over time? Basically… is a server frame an atomic update on the client as well?