Hi
If your partial ordering is modeling "true concurrency" (two events are not ordered if they can be be executed in parallel) for example in process algebra the process (a->x->b)|| (c->x->d) can execute a and c in any order but must wait till both have been performed before the x event is performed by both sequential components. If not you can safely skip the rest of the comment.
Using a true concurrent semantics still equates the two processes (a->x->b)|| (c->x->d) and (a->x->d)|| (c->x->b) which may not be desirable. If you extend the high level spec to include the "location" of events (a1->x1->b1)|| (c2->x2->d2) and now all you have to do is forget the locations in order to retrieve the low level spec.
This may be of no help in you situation but I have found these "located" models useful to map back and forth between automata and Petri net (true concurrent/partial order model) representations of processes.