If you have more than one business, you should be filing a separate T2125 - Statement of Business Activities for each business and only reporting the percentage or share of any expenses that relate to that particular business.
If you have separate business activities and they both meet the qualifications for a home-office deduction and share other current expenses, you must file a separate T2125 for each activity. If you use a separate office space for each activity, simply figure out the percentage of your home that each space takes up, and use those figures when calculating your deductions on the forms. If you use the same space for both activities, you can split the deduction between the two activities.