FC Form Filing

As per 2(42) of the Companies Act, 2013,  "foreign company" means any company or body corporate incorporated outside India which,—

(a) has a place of business in India whether by itself or through an agent, physically or through electronic mode; and

(b) conducts any business activity in India in any other manner.

FC-1 is to be filed by Foreign Companies within thirty days of the establishment of its place of business in India. I don't know what you mean by foreign subsidiary company, but if it doesn't come under the definition above, it is not required to file FC-1.

For details on branch office approval from RBI, please see below link,

Master Direction - Establishment of Branch Office (BO)/ Liaison Office (LO)/ Project Office (PO) or any other place of business in India by foreign entities