Anonymous wrote:Discourage.
They won’t have a sibling bond no matter what. “Special aunt” is the best you can hope for.
Not true. My last two siblings were born when I was 13 & 16, and my brothers were even older. We all have sibling bonds.
But OP, I wouldn’t actively encourage nor discourage. Support what your kid wants to do (it’s also possible she wants to stay close anyway and the baby is her “excuse”).