According to the rules you can do what you propose - the RTW bit is irrelevant.

A related question: I was at SFO recently departing on CX. I was invited to the Sakura Lounge, which is JAL's, but which was staffed by CX (only). Frankly it was a bit sparten.

On the way to the gate I noticed to my surprise that the BA lounge was open because they have a similiar arrangement where Asiana uses it for their flights and staffs the lounge. All the BA flights go much earlier in the day.

For OW lounge access purposes is this still a BA lounge or is it temporarily redefined as an Asiana lounge? I would much prefer to use the BA one to the JAL one if I could (as a OW Emerald). Anyone any experience of trying to access the BA lounge when it is being used by Asiana?