Dear Airline 1

I have not yet had an opportunity to have this suitcase repaired. The suitcase has been taken to my [parents' home/family home/permanent home] in Country X. I will obtain a repair estimate on my next visit there in x months' time, and will be in contact again in due course

That leaves all the options open for now, and you can always decide later. I'd have no qualms about claiming from both airlines; after all, they both damaged it!