Yes, no problem with this. Have done it myself several times.

I don't know whether it would work if you had some other Oneworld FFP status - technically you would only be allowed in if you were booked under the AY codeshare, but as they don't really check BPs at the lounge entrance (as these are very seldom issued for domestic flights) I suspect flashing the correct metal (oh sorry, jewels in the case of OW ) colored card would be enough.