@ANZZ
The DGCA derecogised the Duchess in early 2011 . One of the main requirements to endorse an ME rating is that the aircraft should be registered in India AND it should have a valid Certificate of Airworthiness (CoA) .
The CoA of the only duchess in India expired in 2008 .
Other options to obtain a multi include Piper Seneca , DA 42 and P68 which are available at flight schools in India and hence maintain a valid CoA
Please read this circular inside out as you proceed with the conversion of your DGCA CPL license
http://dgca.nic.in/circular/FCL1_2012.pdf
Going through the CPL application form for issue of license helps clear a lot of doubts as well
http://dgca.nic.in/forms/crew-d/cpl_a.PDF