Not sure what to do with this scenario. I am starting to fly Air Newzealand more frequently. LAX to LHR in Business Class. In December 2020 I want to take the family to New Zealand for vacation, but fly business class - ideally paying with miles. I have 250,000 miles at United Airlines. I have about 100,000 Chase Ultimate Reward Points. My wife has 40,000 United Miles which I plan to transfer to me. My son (14) has 70,000 United Miles which I will transfer as well. I have 125,000 Avios. I will have at least 10 transatlantic trips until next summer.

Should I stick to the native Air Newzealand points program or rather use my United Airlines account number when flying Air Newzealand? I do not care if I buy 2 business class round-trip tickers via United miles, 1 via Air NEw Zealand or if I should aim to use Avios (not sure how much 200,000 AVIOS can take a family of 3).

1. What is most important to you in a frequent flyer program (FFP)?
upgrades, priority services, baggage allowance, good award redemption rates, better award access, lounge access, etc.
>>> Reply: Upgrades and Lounge Access

2. How many miles do you usually fly each year? How many flights/sectors?
less than 25000 miles, 50000+ miles and 20-25 flights, etc.
>>> Reply:
80,000 with British Airways
15,000 with Delta
30,000 with Air Newzealand
3,000 with others (Alaska or United)

3. What fare class do you usually buy?
first, business, premium economy, economy
>>> Reply:

British Airways: Premium Economy + one-way paid upgrade to business at airport
Air New Zealand: Business
Delta: Premium Economy

4. Are you able to choose your airlines and/or class of service? Do you travel for work and/or pleasure?
>>> Reply:

I travel for work. I can fly business class (both legs) on Air Newzealand. Usually LAX to LHR and back. I fly premium economy with BA and pay for east-bound when flying SAN to LHR. Premium economy on Delta.

5. Which routes do you fly most often?
transatlantic, domestic USA, intra-Asia, etc.
>>> Reply:

transatlantic - US West Coast to London (LHR)

6. What is your home airport?
>>> Reply:

SAN or LAX

7. Do you have status in any FFP? What is it? How miles do you have banked in each FFP, if any?
>>> Reply:

Silver on British Airways
Silver on Delta
Nothing on Air Newzealand yet - just started flying with them. One trip completed, second one starting in a few days and 2 more scheduled for rest of year. All transatlantic.

8. What are your preferred airlines, if any?
>>> Reply:

I used to be on United, but due to bad connections out of SAN I switched to Delta (domestic) and BA (international). Just added Air Newzealand and they are great. Will maintain Silver with BA and upon completion each year continue with Air Newzealand.