You may appoint a person as an additional director in the board meeting u/s 260 itself. So you have to hold a BM for the same.
Procedure for appointment of director
1. First collect DIN No. of proposed director and get it approved from MCA. 2. Collect consent letter from the proposed director. (Recommended but not compulsory) 3. Convene a Board Meeting for appointment of director 4. Download Form-32 from www.mca.gov.in 5. Fill form-32 and get it certified from a PCS/PCA and upload the same on MCA site for ROC filing with in 30 days from the date of Appointment of director (Board Meeting).