Does the number come from the manufacturer? Otherwise, I don't see the logic in giving the same floor plan different numbers, I'd have SS2300 and FR2300 for different models with the same floor plan. That way I can use just the numeric portion as a common identifier for sorts and relationshps.
You may have other reasons for the different numbers so however you decide in terms of this identifier, you need to give records for the same floor plan a common value so that you can group on that value in summary reports or via a relationship to get the correct grouping and sub totals. This may mean that you add a field in your table where you put this common identifier separate from the brand and floor plan fields that you already have in place.
That's what I thought...
I have a separate field that shows "SS" or "FR" and it is color coded. So if I just go through and change all the floor plans to a single identifier "2300/01" I can easily tell which BRAND it is. The more I thought about it the more I think that was the right way. Your comment sealed the deal. I'd rather go back and change all the floor plan entries than add a new field to keep track of.