Hello
I just discovered these Behaviour Trees, thanks for sharing about this formalism. If I understand properly, it is a way to define expected behaviour in terms of execution of actions.
If we consider that Functions are actions, then I guess the way to “mimic” BT in Capella would be using Sequence Links in Functional Chains:
I wouldn’t suggest to go with decomposition of function as this is about performing a functional analysis. Neither with modes diagrams representing modes as actions, because they are related to specific components of the system, which will make difficult the task of representing the expected behaviour when actions are executed by several components, and because the semantics are not that close (modes (or states) are not actions, but they can enable actions).
However, Functional Chains and Sequence Links won’t be enough, as semantics such as “find and execute the first child that has not yet succeeded” are not native in Arcadia and would require some extension or some free-text explanaition.
Hop this helps.