How to draw an additional line or arrow between transition and state in PlantUML state machine diagrams - state-machine

Question

I draw two state machines with one PlantUML file, where the arrows between states denote the trigger event (red) and and the action, executed on transition (blue). They live in parallel. One transition depends on a state of the other state machine. I want to indicate this with a dashed line or so.
How can I draw an additional line or arrow between an transition arrow (or even its text block) to a state of another state machine?
My diagrams's code:
#startuml
<style>
stateDiagram {
arrow {
FontSize 10
}
}
</style>
state fork_state <<fork>>
[*] --> fork_state
fork_state --> FireCoolDown_ReadyToFire
state FireCoolDown_ReadyToFire {
}
state FireCoolDown_CoolDown {
}
FireCoolDown_CoolDown --> FireCoolDown_ReadyToFire: \lif ( <font color="red"><b>Timeout (PT0.2S ms)</font> ) {\n <font color="blue"><b>// Nothing to do</b></font>\n}
FireCoolDown_ReadyToFire --> FireCoolDown_CoolDown: \lif ( <font color="red"><b>Event.FIRE</font> ) {\n <font color="blue"><b>// Nothing to do</b></font>\n}
fork_state --> Fire_IDLE
state Fire_IDLE {
}
state Fire_FIRE {
}
state Fire_WAITING {
}
Fire_WAITING --> Fire_FIRE: \lif ( <font color="red"><b>State machine [FireCoolDown] in state [CoolDown]</font> ) {\n <font color="blue"><b>// Nothing to do</b></font>\n}
Fire_WAITING --> Fire_IDLE: \lif ( <font color="red"><b>Event.STOP_FIRE</font> ) {\n <font color="blue"><b>// Nothing to do</b></font>\n}
Fire_FIRE --> Fire_WAITING: \lif ( <font color="red"><b>State machine [FireCoolDown] in state [ReadyToFire]</font> ) {\n <font color="blue"><b>Fire Projectile,</b></font>\n <font color="blue"><b>Dispatch Command with Event.FIRE</b></font>\n}
Fire_FIRE --> Fire_IDLE: \lif ( <font color="red"><b>Event.STOP_FIRE</font> ) {\n <font color="blue"><b>// Nothing to do</b></font>\n}
Fire_IDLE --> Fire_FIRE: \lif ( <font color="red"><b>Event.START_FIRE</font> ) {\n <font color="blue"><b>// Nothing to do</b></font>\n}
#enduml
My drawn diagram:
(I drew a pink arrow as example of how a link between transition and state could look like)