If I have a *G card on one carrier (say, UA), may I access the lounge of another carrier (say. LH) while crediting my miles to a third carrier (say, NH)?

Say I am booked on a LH flight from MUC, which I am crediting to my NH account; I have *G status on UA but not on NH. May I access the LH lounge at Munich, showing my UA *G card?

This is an example and not limited to the carriers mentioned above; I just want to know what is the principle involved.

For that Itinerary your *Gold card would get you into the Business or Senator Lounges, but you would need to be flying in First Class to access the First Class Lounge.

So let's have another example here. Let's say you were a UA *Gold who booked a flight from ORD-NRT on NH and were crediting those miles to OZ. You would be able to use the SK lounge in Terminal 5 even if you were in economy class because you are *Gold. You would also be able to access any of the various United Clubs (NOT the GlobalFirst Lounge though) since you are a MileagePlus Premier Gold member who is flying on an international flight.

One more example: If you were a UA *Gold member flying from IAD-LAX you would be able to access LH Lounges (both Business and Senator) but you would NOT be able to access the United Club even if you were flying in First Class because United does not let their own *Gold passengers in their lounges on domestic itineraries. This is something that I believe is unique to UA (Reasons being the vast amount of passengers they handle as well as them selling memberships to their clubs.), and a Gold member from any other *A airline would be able to access the United Club.

Who you are crediting the miles to, or flying with (as long as any *A airline), is irrelevant as far as *A lounge access is concerned:
http://rg.starallianceemployees.com/lounge-access.html

(with minor caveat for UA US domestic pax and UA US lounges)

The shortest answer to your question is 'yes'!

Agreed!
*G with A3, flew on UA and credited (some) miles to AC.

Many people (particularly as half the *A airlines status match) do this regularly. Just make sure you don't have a zealous lounge agent offer to put the *G card you use to access the lounge in your booking, displacing the one registered.

EXCELLENT advice. Otherwise it is pretty well impossible to rectify the error after you fly... Once the booking FF number is altered and you don't notice it until after you fly.... Sheesh.

As long as the name on the same-day boarding pass matches the name on the plastic *G card shown access should be OK.

Anyone have recent experiences with this at LAX TBIT Star Alliance Lounge? I'm guessing it won't be an issue -- I have a BR ticket crediting to UA and *G through TK.

I thought I maybe had to call to change the FF number on my ticket to TK but sounds like that's not the case as long as I have my physical TK card. Thanks!

UA will typically insist that the *G number be on your BP in order to access the United Club. Although that is not what the *A access rules say . . . .

Not the case in my experience (anecdotal perhaps, but still...), latest experience this past Monday.

Not the case, IME, as well.

In my case, my UA BP shows my UA*G number but I enter with another *G airline card. This necessitates some typing and pecking at their keyboards, but I've never been denied entry. I do this almost every week.

In most cases a *G screenshot works as well. The agent usually types in your number.

That's UA for you - consistently inconsistent!

Has anyone been successful in accessing a lounge without a physical card, particularly Air Canada's lounges? I can screen shot my digital card that clearly shows the airline code, my name, and gold status.