If it comes to strike action, and Lord knows we don't WANT it to, the non-Balpa folk would be well advised to carry on if possible. They have to protect themselves and striking alone without Union backup is not a good plan. I would not try to stop any crewmember going to work.
Better still they could pick up the phone and join Balpa very quickly.
Another very important fact is that any strike action, even a few hours, should be notified WELL in advance and very publicly. We don't want to upset the pax, so give them enough notice to either re-book their flights with another carrier or not book at all in the first place.
This would have the ideal effect of not leaving them 'high and dry' at short notice and 'hitting' (horrible phrase that!) the advance bookings.
The customers are our future and we have no argument with them but the management need to know the score.