For example, if you have a "focus" BDD for a block
Thing, show also in the diagram (with just the symbol and all compartments collapsed) a client UsesThing, which might have a Property t:Thing that can be shown on an Association end. The block UsesThing must of course then also have a linked diagram.
Some purists claim the practice of including a "client" block (or other element) breaks encapsulation because it assumes a particular usage; if the client changes the diagram can break slightly. It can also sometimes block exporting modules because of dependencies.
Another approach is to show at least one diagram symbol that offers a way "up" or "across". This can also, however, sometimes cause dependency problems for exporting modules.