Ok - the more I read about it, the more I get confused.

I am CO FFP member and accrue (or try to) all my miles to CO.

In Asia, I use SQ a lot, and when on an SQ flight, there is no issue (except for giving me 150% miles/points on Y per CO website).

But, I don't understand codeshare flights. If I book on SQ and get SQ 5336 and it is actually MI 336 flight, I know I can get Krisflyer miles for this because the SQ website says I can. But I was certainly unable, using the SQ website, to input my CO FF number to claim there.

But how does codeshare work for SQ in particular and for any airline in SA in general? Are codeshare flights subject to being counted for earned miles? If not, where do I go to find the exclusionary language?

And, when it comes to lounges, I walked into the SQ gold lounge at SIN with a boarding pass that was a SQ piece of cardboard, an MI 336 flight listed on it, and my CO/SA *G card. They let me in.

Does this mean that flying on a codeshare flight also entitles one to *G benefits like the lounge and check in?

TIA

OK - I think I may be seeing the pattern. On Wiki website is http://en.wikipedia.org/wiki/Star_alliance.

Looks like member affiliates would earn mileage across SA, non-member affiliates only with the airline... looks to be same for lounge access?

For codeshare flights, it is the operating metal/carrier that invariably counts. If you buy CO/SQ and fly SQ, which is in *A, then assuming the ticket is eligible for mileage accrual you get elite qualifying miles that counts towards CO status. Likewise, you get lounge access if you have appropriate *A status. If you buy SQ/MI and fly MI, then MI is not in *A hence no mileage and no *A lounge access or luggage benefits. Lots of airlines have their own individual arrangements with other carriers, including codeshares, but they may not apply to the particular alliance they are part of.

This is as it should be; partners of partners do not earn.

Operating metal matters. Nothing else.

They screwed up in admitting you to the lounge; you weren't entitled to such access.

As a general rule, no.

Thanks to all, and in particular, sbm12. I fly SIN-KUL almost weekly. I generally fly MH as I can check in at KL Sentral and avoid the zoo that is KLIA MH economy counter.

I had hoped that if I flew SQ, I'd achieve a few benefits.

a) Accrue mileage and more importantly, segments... but it looks like I can only do this if I exclusively book SQ flights which, on average, are S$70 to S$100 more expensive than MH or MI.

b) Take advantage of the business class line at KLIA... although I think SQ would be loath to turn me away with an SQ reservation code and a *G card.

c) Use the lounges - of minor importance since I do these flights so often, I try to make my time at the airport as short as possible... Sunday evening flights out of SIN to KUL are usually very easy.