i have a request for 12 white & 12 chocolate cupcakes. i really don't want to make 2 mixes (i'm a box mix girl) can i just do the white and add like 1/3 cup cocoa to the rest? should i add some liquid too? i'm to busy to experiment these days. what do you think?

1/3 cup cocoa might not be enough. But yes, that's basically is all you need to do. Maybe melt or add as is some chocolate chips?
Don't have? Chop candy melts.

how much do you think for half of a cake mix? i have plenty of cocoa &/or bakers chocolate.