In Bamboo versions before 3.3 it is not possible to configure multiple depots in a single plan, as per  BAM-678 - Getting issue details... STATUS

Workaround

Perforce has client workspaces which are the equivalent of sandboxes. Workspaces have multi line views which allow mapping from any part of the repository into your workspace.

Have multi-line views in your workspace. http://kb.perforce.com/UserTasks/ConfiguringP4/MappingMulti..Directories

As of server release 2004.2, lower lines that begin with a "+" ("overlay mappings") do not completely override earlier mappings in the previous fashion:

//depot/main/util/... //freds-client/util/...
+//depot/fred/util/... //freds-client/util/...

Instead, overlay mappings override mappings on a file-by-file basis. For example, if any given file exists in //depot/fred/util, then it will be mapped to the corresponding location in //freds-client/util. However, if a file exists in //depot/main/util but not in //depot/fred/util, then that file will be mapped to //freds-client/util instead.