FYI: I have not obtained any hardware, yet, so "just try it" isn't a go for me.  In case the choice of hardware might influence this, I want to get this resolved early, before I buy anything.

My requirement was originally to have 2 routers communicating to each other (actually 4, but each to each other).  But this has changed slightly.  Now there is 1 router (maybe 2) that will not be running OpenWRT, and does no support WDS.  It will only communicate with a client (not an access point, presumably).  Is possible to make OpenWRT talk to the specific router AS a client, without disabling the ability to talk to other wireless devices as an access point and/or via WDS?  Note that if there are 2 such "foreign" routers, they will not be talking to each other (I hope).

FYI: If doing this requires some tweaks at source level and recompile everything, I already have plans to do that, anyway.

Has anyone done this before?