The creation of a business plan is not indispensable for the submission of the application. Nevertheless it is highly recommended that the form is accompanied with a sophisticated business plan because it enhances the elements that show the sustainability of the company. The sustainability of the subsidy receives that 1/3 of the grading during the assessment of the application.
"Because" is OK.
The sustainability of the subsidy makes 1/3 of the overall application assessment grade.