Anna,
I am confused about your description of the chins that you have. I am
assuming you have a homo ebony (solid black) dark pastel, brown velvet and
standards.
The combination of your wording does not make sense to me such as ebony
pastel. There is either a light pastel, or dark pastel. Each has an ebony
background, but in their definition, it is not clear if you say ebony
pastel, what you are talking about.
If you are trying to produce a chocolate colored animal, a homo or hetero
ebony crossed with a dark pastel, or even a beige animal could produce such
a color.
It would be better to cross the dark pastel with the hetero or homo ebony
though as they are both dark bellies.
Hope that is some help to you:)
Sincerely,
Kirsten
Humboldt Hunnies Exotic Chinchillas