Common teams and timelines

Hi all,
In our projects we have multiple teams working for the same release. For each team we created one team area, and we also created one main iteration representing the release (Release 1) under the Main Development timeline.
Each team works in different iterations (lets name them sprints), independently, but all contribute to the same Release 1, so all the sprints are nested under Release 1 iteration, as follow:
--> Release 1
-------> Sprint Team 1
-------> Sprint Team 2
-------> Sprint Team 3
...and so on...

I need to create a dashboard for each team, to track a set of metrics. The problem is that some of the metrics use the tag current iteration to collect the data, and as we have just one timeline, there is only one iteration marked as "current" at every given moment, which doesn't represent what is actually going on (there are four current sprints in parallel, one for each team).
Suppose I separate each team to a new different timeline (in order to have multiple current iterations). This would be a solution, but what I need in this case is a way to share a Product Backlog (actually, the Release 1 product backlog) among the teams.

Do you have any suggestions? I'll appreciate any solution, workaround or even suggestions to re-arrange the teams and timelines in a totally different way.
Thanks in advanced.