14/08/2014 12:54 BST | Updated 22/05/2015 06:12 BST

Three Into Four: Rivalry

Three Into Four: Rivalry

Diana pushed Liv's high chair onto the ground the other day. With Liv still strapped into it.

Thankfully, no one was hurt, but the incident did make me realise that D has reached the aggressive stage of sibling rivalry.

Having no siblings myself, and a wild pack of animals for relations (lots of brothers-in-law, lots of chaos), I didn't really know what to expect Diana and Liv's sisterly bond to be like, other than hoping the stories I heard about my husband bashing his little brother over the head with the yellow pages or a cricket bat (or both? I've heard several variations; my husband looks bad in all of them) wouldn't happen in our house.

Side note: If this were to happen under our roof, it's unclear if my husband would be more devastated about his daughters beating each other up or the damage to his cricket bat. I don't want to find out.

Mostly, Diana is very sweet with her little sister - and in public, where she'll be praised effusively by people other than me, she's a model big sister.

Now that Liv is pulling herself up, D delightedly runs up to her and hugs her, shrieking excitedly: "She's standing up! My little baby is standing! I'm soooo proud of you!" (I wonder who she gets that infectious enthusiasm from?)

And she'll play with Liv, and share her toys and read to her or even help feed her. In fact, sometimes she can be so lovely and blissful that she has me imagining lie-ins a couple of years down the road, where D will fix up breakfast for herself and her sister (and then make another pretend one in the toy oven) while I have delicious dreams about happy daughters...

But then, there are other times when Diana isn't quite so congenial. She'll step on Liv's hands, grab toys from her, push her, shout at her to get away from her puzzle or game and generally boss Liv about in an unpleasant manner.

D's behaviour makes perfect sense to me, and not only because she's coming to terms with having a sister. In fact, she's been pretty angelic considering what we're dealing with when it comes to Liv.

The demon child has grown into a full-on, stage five clinger (with a dash of demon on occasion). I adore her to bits and am pleased that I've developed my own special bond with her that's different to my relationship with D and our dynamic as a threesome, but I am the first to admit that "difficult" doesn't begin to cut it.

Which isn't only problematic for D, it's a struggle for me too. (It doesn't help that my main source of babysitters, my in-laws, called my husband in fear three days before they were meant to look after Liv, wondering if they should buy ear plugs or if she'd decided to deign to drink formula now. She hadn't, they didn't and everyone suffered for it.)

While Liv is getting more delicious and delightful with each passing day - and each new trick - the clinginess is getting exhausting.

If I disappear from view for a second, she will start power-crawling in circles around the room, looking for me and sobbing profusely until she finds me. She sits in the bathroom with me while I have a shower - it's insanity to attempt leaving her in the cot, if only for five minutes - often crying as she bangs on the glass door, trying to figure out why she can't come in.

Stage. Five. Clinger.

Obviously, from D's perspective, I imagine this behaviour is infuriating. Not only is my time consumed with appeasing Liv, the only thing that makes Livvie happy is being picked up, so physically, Liv is also taking over mummy.

An added complication? D and Liv are now officially roomies!

Considering Liv is almost nine months old with no routine to speak of - if she naps in the day I still consider it a miracle of sorts. I need to get my life back on track, clearly, a couple of weeks ago we decided that since Liv is pretty good about sleeping through the night (she usually makes it from about 9pm to 4 or 5am), she was ready to move into her cot in her big sister's room.

Of course, the second we moved her she decided she would rather start waking up at midnight, then two, then three... and then again at five, just in time to disturb D's sleep and ensure she is also up at the crack of dawn. Calling the experiment a nightmare would be a euphemistic way of looking at it.

So I think this new roommate business, combined with Liv's mobility (and every visitor remarking on it), is the reason Diana is feeling a little bit sensitive these days.

I was thinking lovingly about how, just a year ago, when I was pregnant with Liv, D used to pat my belly and tell me she'd teach her baby sister "how to be a lady." I mentioned how happy that made me to Diana.

"I still have lots to teach her, Mummy," D replied. "I need to tell her about all the Disney princesses."

So perhaps all hope is not lost - at least in terms of D and Liv's relationship.

As far as D and princesses, that battle is over. Ariel, Rapunzel and Jasmine have abducted my daughter.