So this might be a dumb question - since I never used it before - My head unit has a source selection for CD changer - as well as CD. - Where is the cd changer?? I thought it was the cd slot but it won't take more than one cd -- or is it just a matter of the selection being there but I don't actually have one??

 

Most only have a CD/DVD and no multi CD changer in the head unit. In my S-Type it had a changer in the trunk, but with the USB stick capability and bluetooth it really makes the multi CD changer obsolete.

 

On the older XF with the 6 CD system (eg the premium Bowers & Wilkins system) like my old XFR had you simply load 6 CDs one after the other into the single CD slot on the dash.
If your CD slot only takes one CD then you don't have the 6 CD system.

 

if this is xf car then you had 6cd changer and at some point it was replaced with single cd disc unit but CCF was not changed. this is my quess

 

My 2012 Portfolio (Bowers & Wilkins) has a 10-CD virtual changer (one slot). You upload up to 10 CD's (takes 10-15 min each) and select them to play or replace. Covered in detail in the manual - maybe this applies to your car.

 

mine is a meridian system I dont think it is single slot changer nothing happens when I try to upload and I cannot put in a second cd.

 

I don't know much about the 2015 XF but I suspect it has the same or very similar system to my 2104 F-Type, which in turn works much like Dick explains above.
I can "load" 10 CDs to the inbuilt hard drive one at a time then play them from the hard drive.
The system copies the content of one CD to the hard drive to "slot 1" then you eject that CD and insert another for it to copy to "slot 2" and so on, and you end up with 10 CDs worth of music on the hard drive.
It doesn't work for DVDs and you can only copy over native CD format, that is it won't copy/load MP3s etc burnt to a CD.
The process is in the audio settings somewhere, from memory go to "Audio" then load a CD and there should be a button on the screen to press saying "upload to hard drive".
Of course you can still play a single CD using the CD player function.