How does PayPal calculate and assign parallel payment transaction fees?

Question

My question involves parallel (aka split) payments in PayPal's Adaptive Payments API.

I have been trawling various forums for the last hour (doesn't help that all the www.x.com pages are gone), and am unable to find a clear answer to a seemingly simple question about how PayPal's fixed transaction fee is applied in a parallel payment.

I can boil it down to two scenarios, but which is correct: Scenario A or Scenario B?

Many thanks,

Ollie

Scenario A: Buyer pays $100 (buyer does not pay transaction fees)

Transaction fees for receivers to split = $100 x 3.4% (variable) + $0.45 (fixed) = $3.85

Seller #1 receives $90, less 90% of PayPal's transaction fees (90% x $3.85 = $3.47) = $86.53

Seller #2 receives $10, less 10% of PayPal's transaction fees (10% x $3.85= $0.39) = $9.61

PayPal transaction fees total = $3.85

Scenario B: Buyer pays $100 (buyer does not pay transaction fees)

Transaction fee for receivers to split = $100 x 3.4% (variable) = $3.40

Seller #1 receives $90, less 90% of PayPal's transaction fee (90% x $3.40 = $3.06 + $0.45 (fixed) = $3.51) = $86.49

Seller #2 receives $10, less 10% of PayPal's transaction fee (10% x $3.40= $0.34 + $0.45 (fixed) = $0.79) = $9.21

PayPal transaction fees total = $4.30

Answer 1

If I recall correctly, the fee is calculated as Scenario A and then split amongst the receivers. You could always test this out on sandbox to determine which method is used.

Answer 2

So after a few inane form letters being sent to me, someone from PayPal responded to my query with the following:

Thank you for contacting PayPal.

From the two scenarios that you have sent Scenario B would apply for the fees on your Adaptive Payment

Scenario B: Buyer pays $100 (does not pay transaction fees)

Transaction fee for receivers to split = $100 x 3.4% = $3.40

Seller #1 receives $90, less 90% of PayPal's transaction fee (90% x $3.40 = $3.06 + $0.45 fixed charge = $3.51) Seller #2 receives $10, less 10% of PayPal's transaction fee (10% x $3.40= $0.34 + $0.45 fixed charge = $0.79) PayPal transaction fees total = $4.30

Thank you for choosing PayPal.

If this is true, I've advised them to make this clearer in their documentation, i.e. that a parallel payment is treated like a series of completely separate transactions, and therefore a full fixed transaction fee applies to each.

If anyone thinks that my advisor from PayPal has it wrong (it's been known to happen...), please speak!