Cousin's wedding resort payment (6-8L+ one time pay) - Best credit card reward strategy?

[pradumn]

Hey

Usage: So my cousin is getting married and I have a resort booked where we need to pay helfty amount(6-8 lakhs or even more).
Requirement: So which is the best card(or cards) which can give the maximum reward for a large one-time/calendar-month/milestone-based payment?
Details: He gets a monthly salary credit of 3+Lakh in account so approval should not be a problem mostly.
Existing Cards: Infinia (RR:3.3%)
Caveats:

• Need the card in ~1 month for atleast the first payment.
• Cant get two Same Bank(Axis) Cards in 1 month AFAIK.
• Don't know the monthly spend limit of the new cards that he will receive.

Options already in mind:

• Magnus/Burgundy: High reward rate (especially Burgundy), but high joining fee for Burgundy might not be worth it for a single transaction.
• Atlas + Amex Travel: Good reward rate potential with milestones, but requires juggling two cards and might not cover the entire amount.

Are there any better Options or tricks I can use to maximise?

<-----------------------------------------------------Calculations----------------------------------------------------->
1. Magnus

• Basic RR: 2.4%
• Accelerated rewards over 1.5 lakhs(RR: 7%).
• Avg reward rate for a 6L(not sure about the limit that would be given) payment(5.85%) ~=35k
• Joining fee gets returned back in form of voucher so only loss of (-4k GST)
• Net: 35k-4k = 31k/6L

2. Magnus Burgundy

• Basic RR: 4.8%
• Accelerated rewards over 1.5 lakhs(RR: 14%).
• Avg reward rate for a 6L(not sure about the limit that would be given) payment(11.7%)
• Con:High Joining Fee(-35K), Diffficult to get in less than 1 month(can upgrade normal magnus later)
• Net: 70k-35k = 35k/6L

3. Mix of Axis Atlas and Platinum Travel(need to choose two different banks to get 2 cards in less than 1 month)
ATLAS:

• Basic RR: 4%
• RR for Resort(I hope so its still in hotel category, will have to confirm MCC): 10% upto 2L
• Avg rewards for a 3L paymentwith milestone(200k*0.1+100k*0.04+5k) ==29k
• Net: 29K-900(gst) = 28K/3L

AMEX Plat Travel:

• Basic RR: 1%
• Avg rewards(in cash) for a 4L payment with milestone(4k+20k) ==24k
• Taj voucher(10K). ->resell-> 8k(ball-park)
• Net: 32k/4L

Net of 3: 60K/7L

Thank You