Let's see if I got this right. Grandma had a sex change and is hot, so your best friend wants to do "stuff" with her and have a grandson who would become grandmas uncle? Or third cousin to Grandma's late sister's three children.
No, I got that wrong. Grandma's sex change would make her "grandpa" so your best friend would be grandpa's niece who is doing "stuff" with Grandpa's grandson, who would also become a cousin to the first male in the family on Grandpa's side, and be the son of the daughter who is married to the father of the two twins who
are from Grandma's oldest living uncle, who was by the way, adopted.
I think I got it. But where does the baby come in?