Flight likely to be cancelled due to announced national strike. What's the smartest move?

Looking for advice.

I have a flight within EU booked from Brussels Airport on May 12, traveling with my partner and our small child. On that exact date, there's a major national strike announced in Belgium. Brussels Airport has confirmed that fewer than half of departures will operate.

My understanding of EU 261:

This is an "external" strike (airport security + ground handlers, not airline staff), so it counts as an extraordinary circumstance so no €400 compensation.

I do still have the right to a refund, rerouting, or care if cancelled.

What I've done so far:

Sent an email to the airline asking for a proactive free rebooking, got a generic reply that didn't address my request.

Planning to call the call center tomorrow morning.

- What should I be doing right now to ensure the best outcome?

- Should I already rebook with the same airline for a fee?

- Is it possible to book a flight with an other airline (cheaper than the fee of rebooking with the same airport)?

The strike is in 9 days. I'd rather be proactive than fight for scraps after the official cancellation announcement when thousands of others are competing for the the same flights.

Thanks in advance for any insights.