Apologies in advance for the long post, but very much appreciate any help you can offer! I have to admit, I'm quite frustrated at what seems to be complete disfunction between supposed partners when it comes to clearly communicating implications, restrictions, and benefits when booking on each others' airlines from each others' websites (not to mention adhering to said benefits). For context:

• Me: Delta Platinum Medallion, holding SkyMiles Reserve Business, Amex Platinum, Amex Business Platinum
• Spouse: Delta Gold Medallion, holding SkyMiles Reserve Business, Amex Platinum (additional cardholder)

Scenario: Booking a round trip for 2 from LAX to VCE (via AMS)
Goal: Pay the least required while still getting the following

1. Economy Comfort seats (free for me, discounted for spouse, based on benefits listed by Delta here)
   
2. Earn MQDs
3. Free checked bag (1 each)
4. [Nice to have] Delta SkyClub access

From what I read, KLM "Light" fares still include STE benefits (like checked bags) and the specific Medallion benefit of free Economy Comfort seat selection for Platinum/Diamonds should be honored? So, I compared booking the Economy Light fare on both klm.com and delta.com (very similar flights on the same day):


Same prices, but in terms of my goals, all over the place:

1. Seat selection
   1. KLM: Allowed me to select seats, but charged us both full price for Comfort
   2. Delta: Unable to select seats at all, just got a button saying I needed to upgrade to do that
      1. **NOTE: When I selected "Economy" on delta.com for this flight, I was able to select Comfort for free but my spouse had no discount
2. MQDs
   1. KLM: Unclear based solely on what I see here, but the fare basis code is VLX76OBA, which I believe is "V" and thus earns at a rate of 5% miles flown based on this page from Delta
   2. Delta: Explicitly says no MQDs will be earned
3. Checked Bags:
   1. KLM: STE(+) benefit, so I believe it should be honored
   2. Delta: Medallion benefit which is honored for Basic Economy
4. SkyClub:
   1. KLM: Based on the following from the SkyClub access rules, we should not have access, but I've found DPs suggesting otherwise. So, unclear, but probably not.
      
   2. Delta: Explicitly says no access to SkyClubs

Now, I haven't tried actually completing a booking with KLM yet, but my hope is that upon doing so (and associating our SkyMiles numbers):

1. The trips will show up in our Delta accounts
2. Economy Comfort seat for free/reduced price via one of the following;
   1. It'll just work on KLM.com/app
   2. We'll call into KLM to have them override the website
   3. We can select the seats with the correct prices on the Delta trip
3. As for SkyClub, we'll just try our luck. If Delta's backend systems somehow don't consider KLM Light fares to be Basic Economy equivalent, then great. Otherwise, we'll live.

Does anyone have any experience with this specifically? It's hard to find recent data points which match this specific scenario. Really hoping we can get a clear answer since booking Light on KLM would save us hundreds, but we just don't want it to be at too high a cost in regards to benefits.