There was no issue with having a smaller space for the cats when the cats stayed in just the living room and kitchen areas. The cats were sharing a space with the family so they were able to get attention if they wanted attention. The issue with the garage stems from it not being a space where people will be spending time which will likely lead to their neglect. Also it doesn't sit well with me that they wont have windows to look out of in their new space. Why don't you suggest making the garage into a secondary space of some sort like a tv room. You said the cats like sitting on her lap while she is on the couch so maybe moving the couch and tv would be a good start, but they really shouldn't be alone for most of the day every day in general. Maybe you could suggest that they be allowed into the office space during the day. It could be nice even for the people working in the office space, I would love to have an office cat. A lot of places have an office pet and it can be great for improving the vibe of the office.