Canista

I’m planning a trip from LHR to LIM.

A typical route could be LHR-MIA and MIA-LIM. From LHR, both BA and AA fly to MIA, and then only AA from MIA to LIM.

Question for the experts is: if I use Q points to book a flight, can I book BA for the LHR-MIA leg and then AA for the following part, all for the combined amount of points (e.g. 160,000 for the 14,000 miles trip in Business) or do I need to stick to AA for the entire trip?

Additionally, can I include a further stop (more than 24 hours), for example MIA-BOS BOS-LHR on the return (so flights would be LHR-MIA-LIM / LIM-MIA-BOS / BOS-LHR, all for 160,000 points in Business, on AA and BA)?

Thanks!!