When has River met with the 8th Doctor, in her timeline?

Question

In Silence of the Library, River says to the 10th Doctor that he's younger than she has ever seen him, but we know that she met him in the Audio Adventures.

RIVER: Thanks.
DOCTOR: For what?
RIVER: The usual. For coming when I call.
DOCTOR: Oh, that was you?
RIVER: You're doing a very good job, acting like you don't know me. I'm assuming there's a reason.
DOCTOR: A fairly good one, actually.
RIVER: Okay, shall we do diaries, then? Where are we this time? Er, going by your face, I'd say it's early days for you, yeah? So, er, crash of the Byzantium. Have we done that yet? Obviously ringing no bells. Right. Oh, picnic at Asgard. Have we done Asgard yet? Obviously not. Blimey, very early days, then. Whoo, life with a time traveller. Never knew it could be such hard work. Look at you. Oh, you're young.
DOCTOR: I'm really not, you know.
RIVER: No, but you are. Your eyes. You're younger than I've ever seen you.
DOCTOR: You've seen me before, then?
RIVER: Doctor, please tell me you know who I am.
DOCTOR: Who are you?

We know that she met the 8th Doctor in the audio drama The Diary of River Song, that were created later (in real time). So, if the Audio adventures were before Silence in the Library, she shouldn't have said that she has never seen him this you.

When she says that he's younger than she has ever seen him, is that a continuity error?

Or is there some other explanation for this seemingly mistake?

Answer 1

River's line in "Silence in the Library" cannot be literally true.

During "The Husbands of River Song," which is chronologically very shortly before "Silence in the Library" in River's timeline, she has a series of photographs of the first eleven numbered doctors plus the War Doctor. Therefore, River has seen all of the doctors* up to Twelve, either in person or in photos. In particular, she has seen photos of the First through Ninth Doctors.

So that leaves us with a few alternative interpretations of the word "see":

1. Seeing the Doctor in person, not counting photography or other means.
2. Conversing with the Doctor.
3. Doing both (1) and (2) simultaneously.
4. One of the above options, but not counting "spoilers" (instances that the Tenth Doctor should not be allowed to know about for timey-wimey reasons).

I have not personally listened to this audio drama, so it is difficult to say for certain which of these definitions applies here. However, looking through the Wikia article and portions of this Wikipedia entry (Ctrl+F "River Song"), I believe that (1), (3), or (4) would work because she disguised herself while talking to the Eighth Doctor and/or conversed only by radio rather than in person. It might still be necessary to hide this information from the Tenth Doctor, or she might not think of this as "seeing" the Doctor at all.

(4) is my preferred solution. River is well known for lying in order to preserve the timeline, and she's very good at concealing her true emotions while doing so (see for example "The Impossible Astronaut," or indeed the whole of Series 6). She knew that she was not "supposed to" acknowledge having met the Eighth Doctor, so she didn't. It's possible that Twelve advised her about this issue during the twenty-four year period following "The Husbands of River Song," but it's equally possible that she was able to discern the problem by herself.

There is also the lazy option of declaring the radio works non-canonical. While this might be an answer, it is not the answer, because Doctor Who does not have a canon.

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* She also indirectly displays knowledge of the Meta-crisis Tenth Doctor by acknowledging that Eleven ran out of regenerations (but is conveniently unaware of his receiving a new set in "The Time of the Doctor").