Trying to plan which program is best to credit some upcoming flights:

I'm about to take a JFK-LHR AA-coded BA-operated W-class PE/WT+ flight
Then early next year, I (and spouse and child) will be flying LHR-CDG on BA in Y, followed by CDG-LHR-JFK in J (R/I class) and In April will fly JFK-LHR-TLV on AA and BA coded flights in discount J. Possibly a few extra segments in Y on a OneWorld airline to get back from TLV to JFK (such as TLV-AMM-JFK?).

Trying to figure out strategy for status and miles collection here...

I was considering doing a Platinum challenge on AA for myself, presumably starting today with the WT+ flight, which would extend for 90 days to cover the LHR-CDG/CDG-LHR-JFK portions but not as far as April for the JFK-LHR-TLV/(TLV-AMM-JFK?) segments.

It is worth paying the extra to do that challenge? If not, how does the double dipping in January affect this for AA mileage/status?

Alternatively, I could credit the flights to Alaska (for our child) or to BA (for any of us). Not sure how that works for partner flights -- anyone here know?

BA seems to be giving Silver (equiv to AA PLT but better because it'd get US domestic lounge access) with only 450 tier points but not sure if that includes extending the tier point collection year. My and our child's tier point collection year ends Jan 8th which would not work for crediting all the flights within the same year. My spouse's year ends in September so that should cover all the flights.

The other wrinkle is that my own CC spend seems to make it likely we'd get AA PLT through me next year even without much flying. What is the minimum spend necessary without flying to get that?

Sorry for the mess of questions. Just quite confused and wanting to decide today...