Your chins can either have black velvet babies or standard babies. The babies eat milk and will eventually graduate to eating pellets and hay with mom. They don't need "extra" unless mom doesn't get milk in. I'd also not offer her for "trade" until you are sure one way or the other if she is or isn't pregnant. Trading/getting rid of a pregnant female is not a good idea.
I'm also confused as to why they were just separated a week ago.
Since you've known since August, shortly after you got them, that they were different genders...as stated in this thread.
http://chins-n-hedgies.com/forums/showthread.php?t=17886
You also posted a thread back when you "first" found out they were different genders asking about a diet for her and saying you had separated them then. Did you put them back together? Why weren't they kept separate?
And did you buy them as a pair as you've stated several times or did you buy her for him as you say here...
But in your first post about Isabella, you clearly state she is a "she". I guess I'm just flat confused by all the contradictions.