Focus of Control and Recursion

[EricT]

In sequence diagrams, is it possible to show recursion across multiple objects?  

What I would like to see is additionnal Focus of Controls upon recursion across multiple objects, much like the second focus of control shown when selecting a recursive call on the same object.

By recursion across multiple objects, I mean:

A calls B, B calls A. Thus, A gets an additional focus of control upon the call from B, until it returns from B's call.

So, it this currently possible? If not, could it be considered as a new feature?

Regards,

EricT