Yes, 2 or 3 adjacent flats can be considered as "one" house property for capital gain exemption: Tax Talk - Readable format accessible at- http://ssrpn.com/article-details.php?id=1468

Partner of M/s. SSRPN & CO. 10, Laxmi Vyankatesh Apartment, Telephone Exchange Square, C.A. Road Nagpur-440008.