I couldn't find a specific answer to this question, so my apologies in advance if this has been covered. I'm and AA EXP and have a BA F ticket booked from SFO to LHR in July. We have another onward flight to ATH four days later...but with the current Covid Green/Amber situation going on, I'm starting to lean on either buying a new LHR to ATH flight for same day transfer, or calling to see if BA would combine my current two tickets so I don't have to cross Border Control. Any thoughts or insight on this? If I had to keep to record locators/tickets, would the agent in SFO combine them and book us through so we only have to transfer in LHR and luggage travels? Or would we have to actually cross Border Control in LHR and then re-check in for the LHR-ATH flights? Thank you so much in advance.