A Proprietorship concern can be converted into the a partnership following the below procedure:
1) Minimum 2 members(partners) to be there to form a partnership
2) By mutual understandings of the partners a deed as to be prepared as per Indian Partnership Act, 1932
3) The partership can be registered under the Indian Partnership Act, 1932
4) If your proprietory concern is registered under various act(s) like Sales Tax, Service Tax or other, then concerned forms to be submitted accordingly to change the status of your firm/business.
5) A seperate PAN has be obtained by the Income Tax Department and accordingly the IT Returns has be to filed. And after conversion to partnership the assets & liabilities of the firm of proprietory concern can be transferred to the firm's name.