Always leave some extra open (unused) connections on the connector pane. You'll save yourself a lot of time and pain :headbang: on that inevitbale day when you need to add some more I/O to a VI you swore you'd never need to expand.
You have to choose a new connector pane, possibly rearrange your control/indicator connections, and start relinking (and possibly rewiring) every instance where you call the subVI...