If what you are trying to achieve is to have a default program in Skyteam, Oneworld and Star Alliance to which to credit your respective alliance flights to, I suspect the easiest for you would be to credit Skyteam flights to Delta. The mileage requirements are not great, but at least the miles don't expire, and you also have the benefit of crediting any LATAM flights you take to them (given that they have left Oneworld and haven't joined any other alliance), as well as any Virgin Atlantic flights until they join Skyteam next year.