I have 3 children, two are primary school age and then I have a bigger age gap to my nearly two year old. I have always tried not to expect or rely on my older child/children to help out with the younger child as I do not feel that it is fair upon them to expect that.
However, it is getting harder not to ask particularly my eldest to help me out. It makes it so much easier to cook a meal if the toddler will sit any listen to dc1 reading her a story. dc2 refuses to go to the toilet alone, and it is again easier on me if my eldest can be persuaded to accompany dc2.
I feel guilty for wanting/needing this help from my eldest though. What do other people do in similar situations/how much help to you ask/expect an older sibling to give wrt the younger child/children?