Hi, I know most of the story so I hope someone can help me.
Spike is wealthy and Buffy works for him. She thinks he's a jerk because he goes through many fiances (they all back out once the realize they won't get anything if they divorce him). Spike is actually testing them to see if they like him or his money. Buffy is a widow and regrets not having children before Angel died and plans to open up a baby store. Spike catches Buffy in his office and they make a deal involving Spike getting Buffy pregnant if she will be his date to a wedding. Everyone in Spike's family likes Buffy.
If anyone can provide me a link or title/author, I would be very much grateful.

~Anna