If I was ever going to have a big age gap like that, I'd have to have 2 close together
My mum had us 3 aged 5,6 and 7 and then my newborn sister.
She was never part of our "group", not on purpose, she was just always so much younger than us, we didnt have much interest in a baby or toddler and by the time she was a child we were teenagers who again, were not really interested in a small child.
We were all nice to her, but none of us are close to her and even to this day, she is still the "annoying" younger sister because of the way she now behaves. It's a shame too because I try really hard to like her, but she is so very annoying and attention seeking.
I blame the way she is on her technically being a single child. I think if she had had a sibling around the same age she wouldnt be the massive attention seeker she has always been
I have 2 children, aged 6 and 8 and if I was to ever have another, I would definetly have to have 2 because of the way I've seen having one play out in my siblings