06/05/2015 07:07 BST | Updated 05/05/2016 06:59 BST

Dear Princess Charlotte - From One Second Born to Another

Welcome to the World Princess Charlotte! I know you are only a few days old, but I wanted to give you the low down on life as a little sister.

I hear your elder brother George is quite a big deal. My big sister, Freyja, is too. At least that is what it feels like sometimes. For a start, she had a baby book which is at least partly filled in. Mine is completely blank. I am not even sure if my parents have even opened it. My mum's phone is full of baby photos of her which all look exactly the same, but apparently she is making slightly different expressions in each one. As for photos of me when I am a baby - in the majority of them I am being photobombed by my big sister. Otherwise they are carefully staged pictures of Freyja holding me (being hovered over by my mum) whilst smiling lovingly at me. Of course the photo showing this that they put up on Facebook is the one from thousands where I am not screaming, or being poked in the eye by my "loving" big sister or that she isn't sobbing with the realisation that she is no longer an only child.

The thing is, your parents have already had a "practice" at being parents with your big brother. They won't panic at an exploding nappy or put the clean one on backwards, and they will know the difference between the "hungry cry" and the "tired cry". They will have all the basics sussed. Unfortunately it does mean that they won't come running to you the moment a cry leaves your lips and in situations which would have had your mother Googling "what to do if my child eats sand?" they are more likely to take a photo and stick it on Instagram.

Then there are all the hand-me-down clothes. I was lucky in that I had an elder sister and got some pretty dresses, but I also had the "slightly stained" babygros. If you aren't happy with what you have been dressed in, make a point sooner rather than later and puke on it.

I know I don't seem to be selling this "little sister" thing, but honestly, it is great having an older sibling. Firstly, there are the toys. There will be all the baby toys that George had AND then you will get toys bought for you "to keep things fair". However, you will also get to play with George's toys and because they are "big kid" toys they will also be really cool. And as a bonus, you won't need to share any of your toys because George won't want to play with "baby toys". Of course if George does remember that some of these baby toys used to be his, scream every time he touches any of them. This will usually result in a reminder from your parents that he needs to "share" and "set an example". It is really important to emphasise to George the impact you are going to have on his life from now onwards. And do try to get some smacking/scratching/biting in whilst you are young enough to "not understand that it is wrong".

Secondly, there is the TV. George probably had his TV watching carefully monitored. Well, the rule goes that you watch TV when he is watching. And no CBeebies for you. You get to watch "big kid" channels, and programmes like Peppa Pig. You will even get to watch Disney films. No children under the age of two have watched Frozen UNLESS they have an older sibling.

Finally, there are the older friends. Your parents probably made loads of friends with children the same kind of age as George and have fostered these friendships through play dates. However, this isn't going to happen as much second time round. I know this might sound bad, but instead, you will get taken along to these play dates, and rather than having to share a dribble-covered Sophie-the-Giraffe with a child who is unable to hold up their own head, you have a new house with a whole host of "big kid" toys to play with. And whosever toys they belong to is now also being told to "play nicely with the baby". In addition to this, as you get older, you will know all these "cool older friends" and may even have an older boyfriend. This will be the perfect opportunity to make up for any times that you feel your parents haven't worried about you enough when you were little.

So Charlotte, I hope you feel reassured that second born isn't second best. Big siblings are always there to "set an example" so bear this in mind and make sure your behaviour is never better than your older brother's - you can always get out of any trouble with a "cute look" so do try to perfect this. One final cautionary note - never "purposefully" try to get George in trouble as one day you could find that your big brother is also your best friend.

Love from Emily x