How do you prepare them.

Kiya turned 4 five weeks before Josiah was born. The whole pregnancy, we talked with her about the "baby in Mummy's tummy", and how she was going to be a big sister. She would look through pregnancy books with me at the pictures of how the baby looks at different stages and I would get out a ruler once a week and measure on her hand/arm how long Baby was at that stage and what they were doing (growing/developing, bones growing, able to hear, able to see etc).

Kiya is a very inquisitive child, and is quite scientifically minded. She would ask rather specific questions about what Baby was doing (and how it got there!) and loved to put her hand on my tummy and feel the movements.

Haleigh was 21months when I had JAmes.
We bought her a baby doll and taught her how to look after it as if it was real.
We talked to ehr about baby, and I let her touch my bump when James moved she came to the scans, midwife/ specialist appointments.
She loves James to bits more so in the last few months now he can be awake alot longe and she can actually interact with him more.
We had a few incidents of Haleigh standing on JAmes's back and getting a bit rough with him, but she quickly realised that wasnt on.