There have been many posts similar to this from different Unit types. The issue is the same across all Units it is not possible to assign a user to more than one Patrol. If you add your support for this other main thread and enough others do as well it will get prioritized higher as a new feature.
I read farther on one of those and perhaps this will never be done. It is quite complicated. So unless it gained a huge majority of users support I don’t thing this will happen.
As Aaron has shared, this is not a feature we are equipped to add at the moment. We are a very small company (only 3 people) and this would be a very complicated and time-consuming process to add this feature. We would love to be able to implement it, but it isn’t in plans for the near future. Right now, the current workarounds are giving a leader troop privileges, creating two separate accounts for that leader (one for each patrol), or combining the patrols into one.