INTEGRATED HQ MINISTRY OF DEFENCE (Mod) ARMY

The Senior most of the armed forces services is the Army. It would be pertinent to begin with them.
For starters other than the nomenclature in the title of this post there is no integration with the MoD of Army HQ. The HQ consists of two branches that is the Gen Staff Directorates & the line Directorates.
The control of both these branches is exercised at the apex level by the COAS & VCOAS Secretariats with the COAS & VCOAS heading them respectively.
The COAS Secretariat: - This consists of the COAS, A four star General, his Military & Deputy Military assistants, His A'sDC both ceremonial and security, His electronic warfare assistant and a liaison officer who interacts with the Army Wives Welfare Association. In addition he has a JCO ADC, & other administrative staff to allow smooth functioning of both the COAS office & the Army House.
The VCOAS Secretariat: -  This is almost a duplicate model of the COAS secretariat. Only that he is a three star General in the rank of a Lt General but status of an Army Commander (GoC-in-C).
DCOAS (2)    Two officers of the rank of Lt Gen but with status of a Corps Commander (GOC) are assigned to these posts. They are responsible for (Information Systems & Training) & (Planning & Systems) respectively.
The above appointees are assisted in their day to day functioning by five Principle Staff Officers, viz, Adjutant General, Quarter Master General, Military Secretary, Engineer -in- Chief, & Master General of Ordnance. They are of the rank of Lt General. Other than the Engineer-in-Chief the other appointees could be from any combat arm.
The Combat Arms Directorates viz, Mechanised Forces, Artillery, Air Defence, Signals & Aviation. All headed by Officers from these specific arms of the rank of Lt General and is one leg.
The General Staff Directorates that form the other leg of the organisation of Army HQ include the following: - Military Operations, Military Intelligence,Military Training, Perspective Planning,& Staff Duties. Other than these the other functional directorates are those like, Border Roads, National Cadet Corps, Military Nursing Service, Medical Services (Army), Health Services, Postal services, & Military Police.  These are headed by officers of the rank of Lt General, specific to specialised entities like the medical stream & border roads but from any arm or service for the others.
All of the above are assisted by a number of junior officers from all arms and JCO/OR from the clerical cadre. The offices are located mainly in South Block & Sena Bhawan with  others being in Delhi Cantonment.