Branches? Inside the same FSM?
You cannot do that.
Contrary to other visual scripting tools, there is basically one single flow and one single path followed by this flow, inside your FSM.
If you want two behaviors/scripts to run side by side (in parallel), you must use two FSMs, possibly on the same Game Object if it makes sense, and come up with a way for both of them to communicate; preferably with one FSM being more like the main one and the other being the satellite FSM, checking for changes in floats, bools, etc., or listening to events on its own and, if it gets triggered in a given way, then do something like, for example, forward an event it received to the main FSM, or send another one that's unique to both main and secondary FSMs, all of which will allow you to reroute the flow on a different path in the main FSM.
You can also use the Go To State action, it works inside a FSM is also trans-FSM and can help you avoid creating another event if you're sick of using so many events.
Also, this is where the actions that allow you to edit or keep an eye on FsmVars in other FSMs become useful. Some are found under Logic, others under the State Machine category (the reason why is more of a mystery).
You can also use the action that checks if a FSM's flow is a given state:
Get FSM State.