Jane Cousins - AUTHOR

I'm not talking about deceased authors whose estates have designated a new author to carry on the series.  Not something they could keep secret when the original author is pushing up daisies. Couple of authors come to mind - Virginia Andrews, Lawrence Sanders, Ian Fleming etc

I'm talking about current writers who perhaps neither have the time nor inclination to churn out books fast enough to meet the schedule set by their publishing company.

I was reading a review of JD Robb's latest work 'Festive In Death' and the reviewer stated they believed that JD Robb wasn't the author.  First, I was shocked by such a claim but the more that I thought about it the more their rather well laid out argument resonated with me.
There were several aspects of 'Festive' that hadn't rung quite true for me.  Peabody is no longer the strong, ambitious detective she had at one time been developing in to.  Now she was all about the pink coat, and the pink boots and squealing over pink things.  Feeney's character (brief appearance) failed to ring true and a host of other favourite characters appeared to be reduced to a sentence or two and had become caricatures of themselves, with no depth. 
The story itself was a repeat, we've done Christmas, we've done Eve reluctantly being roped into helping organise a party/being social - and as always it turns out incredibly well.
I had to ask myself - the question the reviewer had raised - just who had written this book?  At the very least it raised some suspicions and got me thinking.

Which led me to another favourite series of mine - Thea Harrison's Elder series, which I have loved from book one - with the glaring exception of her last book 'Night's Honor' - (and this is just my opinion) no way could this book have been written by Thea Harrison. 
For one, there wasn't even a glimmer of her usual sense of humour present.  The story itself was nonsensical.  Set outside the Elder world we are familiar with.  The romance... quite frankly, bored me.
Maybe I just don't want to believe Thea wrote it.

No, I hear you cry.  That sort of trickery can't be happening.  Why not?  Publishing companies often buy the rights to a series.  The original author would still be paid for the use of their name.  And in the end, publishing is all about the money.  Releasing two/three books a year is way more profitable than a slow author who can only produce yearly (or longer).

I have no clear proof this is going on.  But I would be very surprised if it wasn't. 

Honestly, if the book is well written, set in the world I've come to love and the characters stay true to form - I doubt I'd care. 
On the other hand, when a series takes a sudden swerve, characters behave against type and the magic that had originally attracted me to the story has faded - I have to ask the question.
Just who is writing my favourite series these days?