I have 2 girls. Actually 4 years apart but as DD1 has Down's syndrome she's not your regular 5 yr old and the age group seems closer.
They've only had 16 months with each other but yes they get on well.
Dd1 likes to pi9nt out things to DD1 while in the car and they hold hands in their carseats. The second DD1 wakes up and I open the door to her room her first words are her sisters name. Ddi totters up to DD2, lips ready puckered for a kiss. They lay in DD1s bed together drinking their bedtime milk and waiting for a story. They play in the garden in the sand pit and the playhouse. If DD1 gets nervous at the farm feedignt he goats she sends DD1 in to do it. If DD1 needs medicine DD2 has to have some too. Basically, it;s bloody great.
However, DD1 suddenly wants to play with all the baby toys again and can snatch them from DD2 causing her to scream a scream from the depths of hell itself. An dif I hear the word 'mine' once a day I hear it 57 times (before 10am!) You absolutley need 2 of EVERYTHING! DD2 can be a little rough with DD1 who is a little sensitive and that causes a few tears.
On the whole for 2 very little people they get on well and I love having 2 girls.
DD1's reaction to her siter when she arroved was one of sheer joy. I think it helped that she saw her be born at home and I think that really did make it all seem normal and ok. She was lovley with her. I used to express a little bit of milk so she could help feed her.
Congratulations