How do you do groups of failbacks? For example

log { filter(f_filter1); destination(d_file1); };
log { filter(f_filter1); destination(d_file2); }; <-- log here only if the above fails
log { filter(f_filter2); destination(d_sql1); }; <-- may include messages from the above 2 lines
log { filter(f_filter2); destination(d_sql2); }; <-- log here only if d_sql1 fails

So, say lines 1 and 3 both fail, lines 2 and 3 should both start working. If I put a fallback flag on d_file2 and d_sql2, and d_sql1 fails, d_sql2 wont kick in on matches that d_file1 is still taking.
It seems like there should be a way to do "log { destination(...) or destination(...); };", or "log {...} or log {...};".