You can use a RoutePolicy, to start the other route, when you are done.
Another alternative is to check whether file A has been moved, before picking up file B is allowed. So you can use a custom filter in your consumer, to implement this logic
Using the filter option
Then you can return true|false from the accept method. Then only return true if file A has been moved.
Thanks a lot for your precious help. I'll try that as soon as possible.