Imaginary friend-type scenario involving a toy

[newnamesamegame]

My 4 year old DD has suddenly started constructing elaborate stories about a toy she has and at the moment will constantly interrupt me when I'm talking with other adults and interject with a nonsense story about the antics of this toy.

It seems to happen as a response to her not getting my attention -- we were recently on holiday with my much older brother who I don't see often and more or less every time he spoke to me she would interrupt with a comment about what this toy had done.

Initially I wasn't worried about it but it seems to have spiralled a bit and frankly is very irritating now. She is starting school next week and I'm slightly worried she will go on at length about this toy with other children who will be far less tolerant.

If its relevant, her father and I separated a few months ago. Generally she has taken this reasonably well and her father is still a big part of her life, but I can't help wondering if its connected.

Should I address this head on and gently ask her not to keep talking about this or should I just let it run its course?

I'm completely unqualified for this, but I hope I can help?
From what I know about child psychology these years are when short term memory is developing, and kids often have a habit of needing to tell you everything before they forget it. That's annoying in itself, but it knowing when to interrupt requires cognitive skills to anticipate and judge that she simply hasn't had chance to develope yet.
When it comes to the toy constantly being brought up, perhaps it is a form of buffer, in place of trying to constantly demand your attention directly, perhaps she's drawing you into something she feels is important to garner your attention? Have you tried setting up a hand signal with her? Something as simple as asking her to just place her hand on the crook of your elbow would perhaps make her feel she doesn't need the toy to approach?
If the attention is control based, as in she has to be with you at all times, I would try giving her an element of choice whilst you have to finish off tasks, or make a call. Such as, "xxx, I need to make an important phone call. Whilst I do that do you want to play with a toy, or read a book?". Some kids fall for that trick, some don't :(
Best of luck, and be patient, she may be more stoic than you realise and taking in any stress at home.

No advice I am afraid, but my 4 year old is exactly the same, I am sure it's due to me having a baby recently and starting school next week.
When he interrupts to tell me about his 'friend' I tell him to wait until I have finished and I then ask him questions about whay he was going to tell me. It doesn't always work though!

SympatheticCynic thanks, that's interesting and makes sense...

I think its relevant that my brother and my dad, who she has spent a lot of time around recently, are both highly articulate people who can sound quite intimidating and are not terribly good at "baby talk". She struggles to cut through the high-minded stuff and feels left out and this is her way to compete.

But the suggestions are good ones, thanks...