Yes, you can add one for each business.

For the vehicle, the program already prorates the expenses based on the mileage you enter for that business.  So there would not be any 'double dipping'.

For the home office, I would just manually prorate the square footage of the home office.  For example, if it was 300 square feet and used equally for three business, I would enter it as a Home Office of 100 square feet for each business.  Then the program will take the appropriate prorated deduction.  You can name it something slightly different, such a "Home Office A" and "Home Office B".

Actually, if all businesses were profitable and the home office deduction isn't obscenely large, I would probably just 'cheat' and just enter the entire home office under the largest business, and call it 'close enough'.  CAGMC.