Looking for advice on where we stand with part of our flights being cancelled following Jetstar Asia's closure. Apologies as newbie if I'm posting in the wrong thread, however we booked a holiday package via On The Beach with flights provided by BA via codeshare. The outbound flight is LHR-DOH-HKT (Qatar) and inbound flight HKT-SIN-LHR (Jetstar/BA). Our outbound flight is on 11 Aug returning 24 Aug and it's the HKT-SIN leg that's been cancelled. Our preference is a rebooking for the inbound flight, however appreciate that HKT-SIN may not be a route that BA/oneworld operate on with other airlines, so we were hoping a re-route with Qatar via BA for the entire return leg would be possible (HKT-DOH-LHR as per our outbound flight). We hadn't been notified of the cancellation officially by OTB until today which was the day after I found this out for myself by checking "Manage My Booking" via BA website. Called OTB yesterday and they sent email to BA to ask what our options are and BA's response this morning was as follows:"At this moment there is no policy yet, that has been specified for the cancellation 3K 536. As travel is only in August, passengers are more then welcome to wait a bit to see if there will be any policy put in place. If not then passenger will be eligible for a refund."
Surely they should have a policy in place by now given closure was announced 11 June!? Despite OTB being the agent in this case, I contacted BA to understand what our rights were and they advised OTB should be looking to rebook us. Later spoke to someone at OTB and pushed for alternative flights to be offered as this was never offered to us, just a refund up until that point. We're reluctant to go down the refund route as this is a family holiday booked between be and my sister for 10 of us via 2 separate bookings and finding an alternative in peak UK summer holidays for a large party is going to be challenging and we won't be compensated for having to pay more on a rebooking! OTB have said they will request the option of alternative flights with their travel supplier who are Aviate, however are suggesting that they may not be willing to do so if the cost of the rebooked flights is more than the original flights - can they do this? OTB were still waiting for a response from Aviate this evening when my sister followed up.

Are we covered under EU261 if part of the flight is operated by BA even though it's the non-EU leg that's been cancelled? Where do we stand as the booking has been made via the Travel agent, it is the agent's T&Cs or their supplier's, feels like this is a bit of a grey area because we haven't booked with BA directly and OTB book through a 3rd party. We just to want check if Aviate or OTB have the right to refuse to offer a rebooking before they attempt to fob us off.

Any guidance would be greatly appreciated.