I loved it! I thought the part about the oven was cute.

Is the kid's name Grace or Andrea? Is there a prequil to this so that the story might actually make sense?

I agree wiht Verbena. You need to explain who Andrea is, where she comes from etc. You started to explain it a bit then just dropped the line. Also, do reread your stuff before you post. The Andrea/Grace thing was very sloppy.
in the store when Richie was talking to mac, he was rambling and making no sense, at least to me. You might want to be careful of that. I couldn't follow who was trying to figure out who. At first i thought Mac was wondering about richie, then richie about mac and the find out its richie about grace. And if mac already had this kid why did he let Richie move in? did the meet under the same circumstances?
As for the rest of this. It seems that it can pan out into a cute story. Just don't rush the story. Take time to develop the characters and make it more believeable for the audience.

If you write chapter two please do your readers the courtsey of reading through your work before you post. You call the same character Andrea and Grace which is just sloppy and makes us thinks you don't care about your story.
You also need to take more time to introduce your Universe if you are going to depart so far from cannon - how come Duncan has this small child by this other woman when he and Tessa have been together twelve years? How come he can suddenly have children?
It is a cute idea, but you need to put more thought into it if you are going to do it justice.