
So you don't think she takes after her namesake (Ms Bussell) then? You're not getting her fitted for a tutu? ;) :D
The best way to change from one complete food to another is to give 3/4 of the first food mixed with 1/4 of the new food for a few days, then change it to half-and-half for another few days, then 3/4 of the new and 1/4 of the old till you run out of the old!
To get the quantities right, weigh out a day's ration of each food and divide those into the correct proportions of each - you usually find that different foods need to be given in different amounts. If the packet says (say) 250g - 300g for a labrador, I would start by giving the 250g, not the upper end of the scale.
Hope that isn't as clear as mud - I know what I mean!
:)