I have a slightly different understanding than @MarkHunte’s.
Your request as I understood it was using “Mouse Over” (play timeline forward) & “Mouse Out” (play reverse timeline). The selected timeline must finish before others can play.
If the user can simply slide the mouse around You need to disable the 2 buttons that are not playing their timelines otherwise the user will be confused as to what is going on. The standard way to do this is giving a visual indicator the button is currently not functional.
In this demo the disabled buttons go grey until the timeline is finished “reverse” playing for the selected (“Mouse Over”) button. As soon as the mouse is moved off the button the timeline reverses and then all the buttons become available again.
On-line Demo here.
Hype Project file: Timeline_Delay.hype.zip (16.0 KB)