Is this nested ticketing?

All of these trips would be credited to my SkyMiles Account and all would use GUC’s. Each trip is booked directly with the airline being flown.

Trip 1 outbound, ticketed and flown on a SkyTeam Partner. JFK-CCC with a connection at BBB.

Trip 2 outbound, ticketed and flown on DL. CCC-EWR with a connection at DDD.

Trip 2 inbound, ticketed and flown on DL. EWR-CCC with a connection at DDD.

Trip 1 inbound, ticketed and flown on a SkyTeam Partner. CCC-JFK with a connection at BBB.

If this is nested ticketing, would changing EWR (co-terminal to JFK) to BOS/DTW/??? cure that?

(The gyrations we go through for MR’s amaze me.)

No. Nested ticketing, which DL refers to as back-to-back ticketing, is only an issue if you are doing it to qualify for cheaper roundtrip fares with a minimum or Saturday night stay requirement. It basically requires the "nested" inside ticket to be booked in the reverse direction of the outer ticket -- https://www.delta.com/us/en/booking-...s-restrictions

For example, DL has roundtrip fares with min-stay/Sat night stay requirements on DTW-SFO for $359 roundtrip (with 3 week advance purchase). However, if you don't meet the min-stay requirements (for example, you are doing Sun - Thu trips), the cheapest fares are $497 roundtrip. So if you are making regular, weekly Sun - Thu trips, you can purchase a Thu - Sun roundtrip for SFO-DTW nested within a Sun - Thu (departing Thu of the following week) DTW-SFO ticket. Both of these tickets will meet the min stay requirements for the $359 fares and you will effectively have two Sun - Thu DTW-SFO roundtrips for $359 each instead of $497 each.

This would be to meet requirements for GUCs. slightly different schedule though.

Trip 1 outbound on Day 1
Trip 2 outbound (effectively a return from trip 1) Day 3
Trip 2 inbound (positioning for Trip 1 inbound) Day 14
Trip 1 inbound Day 16

Added: Trip 1 requires at least a week duration in order to use GUC's and I don't want to stay for a week.

I used to do nested tickets on flights DCA-BOS when I had to make multiple trips in a single month. I would buy a roundtrip on US Air (yes, it was a while ago!) originating in DCA, with a return date from BOS three or four weeks out.

I would then buy a nested flight on DL or JetBlue that originated in BOS, but was nested within the dates of the US Air ticket. This resulted in a significant savings. DL or JetBlue never wondered why I was originating a round trip from Boston when my address was in DC.

I just had to remember, on each leg, which terminal to go to....

Okay, I suppose it could be if the JFK/EWR-CCC + nested CCC-JFK/EWR fares (there are probably the same fare filings for JFK and EWR if international) are cheaper than two JFK/EWR-CCC roundtrips (because they are roundtrip fares with min stay requirements). The connecting airports and GUC usage don't really have any bearing. I doubt they would actually go after you, but technically it sounds like it might be a violation.

The classic nested ticketing they are trying to prevent is the guy in ATL working in NYC most every week who flies on interleaved tickets to avoid the higher priced Mon-Fri lights.

If what you are seeing is cheaper fares that just happen to be interleaved, that is not in violation of DL's written rules, and nothing to be worried about.

EDIT: I am assuming that the flights not violate a stay restriction of some sort if booked "normal".

EDIT2: No idea about the GUC issue.

The total fares would be within a $100 range.

How would DL know what the fares for Trip 1 are since it's booked on another carrier?

If it's booked on another carrier, it wouldn't be an issue. The ticketing rule prohibition only covers cases where the back-to-back ticketing is done with both tickets on DL. I guess they might care a little if it's another carrier where DL has a revenue sharing JV, but it's not really covered by the rules. But as noted above, as a one-off itin this is not something they would look at (even if both tickets were DL) as they really only care about the habitual offenders who do this week after week. I'm still a little confused by the itins. It sounds like you are making two short trips from NYC to CCC and spending Day 3 to 14 in NYC. I suppose if these are mileage runs that makes sense. Not really sure what the point is otherwise.

Most TATL routes still have cheaper fares for Saturday night stay roundtrips, but the fare differences are pretty tame since Covid hit (particular from competitive markets like NYC). They can still be significant from less competitive markets. A mid-week trip on DTW-AMS on DL with a Sun or Mon departure and 3-day stay goes for around $1500 roundtrip. But with Thu or Fri departures on this route and same 3-day stay (giving you a Saturday night stay), the roundtrip fares are only $649 due to the cheaper Saturday night stay fares.

Thank you, I'll give it a go based on the responses.

Yes, as I alluded to in the original post, it is an MR. Actually 2 MR's. I'll leave NYC in the evening and return the afternoon of the following day or the day after. Then a break of a week or so and a repeat. I'll do 2 of these next year which will give me most of my DM MQD's. Thanks to all of the rollover, I have sufficient GUC's to use.

The intervening time in NYC is at one of our homes and offices. I'll sandwich my monthly NYC work schedule with these MR's.

Hey guys is the sat night stay over thing still around. I thought all the carriers eliminated the weekend thing.

It's still very much a thing. I've posted a couple of examples directly above (DTW-SFO and DTW-AMS have fares with roundtrip booking and Saturday night stay requirements on DL). They are less prevalent domestically due to competition from airlines like WN and AS who do not have Saturday stay fares at all and everything is one-way's (and the legacy 3 tend to match their fares on non-stop routes where they also have flights). For TATL fares, they are still commonplace. Airports that don't have much non-stop competition from WN and AS and other LCC's tend to have more of them domestic routes. The fare differences tend to be less dramatic domestically. As I posted above, the difference between the cheapest DL roundtrip fares on DTW-SFO with a Saturday night stay and without is $359 vs. $497 roundtrip.

No issues on the ticketing. Just plan accordingly, however, as any issues on the outbound itinerary may impact your turnaround itinerary on separate tickets. You would be marked as no-show on the inbound, and the rest of your downstream 2nd itinerary would be cancelled as well.

Thanks for the caution. All of these have overnights between the applicable trips so there's time to deal with delays and cancellations.

DL policy is to rebook over different tickets/PNRs during IROPs, including flights on certain partners.