Can I claim EU flight delay compensation if I rebook the outward ticket to another date?

Question

My flight A will be delayed by 48h.

According to EU regulations it seems I'll be able to claim concatenation for the delay. https://europa.eu/youreurope/citizens/travel/passenger-rights/air/index_en.htm#shortcut-16-compensation-delay-at-arrival

1. I'm considering changing the outward flight to another date, but I'm worried this might have an effect on the compensation eligibility? Would this cause any implications?

2. In addition I've changed the flight date, of another flight ticket B (with another unrelated airline/flight). There was a considerable cost for this. Will I be able to claim this fee (in whole or part) on the from the Airline from flight A?

Answer 1

I ended up changing the date of the outward flight (free of charge), I also received the full compensation amount (British Airways).

Upon enquiring about compensation for the cost of the change of dates on the unrelated airline, this was rejected.