PC Type1 --> Mac conversions with Mac TTPro - breaks italics in families

I'm using a TransType Pro on a Mac to convert a huge library of typefaces from PC Type 1 to Mac. The faces convert, but the converted fonts italic faces convert to Roman faces. For instance:

Univers
Univers 55 Roman
Univers 55 Oblique
Univers 45 Light
Univers 45 Light Oblique
Univers 65 Bold
Univers 75 Black
Univers 65 Bold Oblique
Univers 75 Black Oblique

Converted as a group to OpenType, the conversion ends up with the Obilique fonts all mapping to their Roman (non-oblique) siblings. I've not changed any of the default settings.

I need the families to convert properly. Is there a workaround for this? The whole thing seems very counter-intuitive (and I say that having been a long-time user of Fontographer, so that's saying something.)

Brad