I am the mum of a child with a neuro disability and I do understand your fears but hope I might offer another perspective?
I am not sure what split mind syndrome is. I had a look at this. People with split brain syndrome living their lives with their joys and sorrows just like everyone else https://www.youtube.com/watch?v=VHgClWAPbBY
All I know is that when your child comes you will love her/him with their disability too. I would never swop my child for one more able. There is an amazing bond even though others cannot always see it. I am so so happy.
A child conceived by egg donation will still have a biological mother (the egg donor). And to support such egg donation is to create children in order to deliberate separate them from their biological mother.
What if the child conceived by egg donation has some other condition that is difficult? Would you wish you had just taken your chances on the natural child you would have had with your partner?
Maybe do not worry about your child as a 'possible condition' . She/he will be someone you will absolutely and helplessly love -even much to your own surprise.
There is a great deal of support for parents of children with disabilities locally. My child's condition has brought our family into contact with wonderful people we would never have met otherwise. I am very changed.
When the time comes we are capable of more love than we know.