There is an issue with the CAS that shipped with Pets, Sims 2’s latest expansion pack. If you create a family w/ a pet and then move them onto a lot, your Sims faces will change (see left picture). What you have to do is create your Sims first. Then exit out of CAS. Then go back to CAP and create your pet. In the neighborhood screen, you’ll see your pet all by him/herself and your Sims in another. Move the Sims first. Then move the pet. Voila! Your Sims will keep their same faces (see right picture).
*shakes fist at EA* Thanks for releasing such a buggy EP.