Thank you Richelieu for this fantastic FAQ covering a lot of the common questions that us A3 *G status holders frequently encounter.
3g. Getting benefits while crediting to another programme
It is possible to use a *A card to get benefits, like lounge access, while crediting the miles to another programme. PNRs have two different fields for entering the mileage programme used for credit (FQTV) and benefits (FQTS). Nothing in the term and conditions say you can't. It has been rumored that A3 is frowning upon that but it's unsubstantiated so far. This FAQ will we updated if A3 introduces crediting requirements in the future.
Just to let you guys know that I have heard of an issue with the situation described above. I have a friend currently battling a case with LH who are not crediting miles from a TK flight on to his Miles and More account after using a A3 *G card to access the TK Lounge Istanbul. The original boarding passes indicate LH * status. LH claims that TK is not confirming the miles were earned.
I will let you guys know when I find out more/if the situation gets resolved.