Can I tap into collective expertise on how best to get to Seoul while accruing Avios and TPs (so a OneWorld airline), in June 2025?

BA not offering any options to SEL at all, and other OneWorld options are uncompetitively expensive.

I note that BA LHR to PVG is cheap (£1300 CW one-way looks a relative bargain), and onward connections via KAL are cheap with 3 flights a day. But I am wary of a split itinerary across airlines, as it would be a real drag to have a BA flight delay or cancellation and it be my problem to resolve, with a jet-lagged family and in Shanghai.

Am I worrying too much about an unlikely problem? It seems BA has no option to Korea - have I missed an obvious option??