Is there any special deity dedicated for sri vidya upasana? I heard that it can also be done along with worship of Lord Narasimha, Lord Ganapathy etc. Is it true?
Sri Vidya is essentially about worshipping the Supreme Goddess or Sri Lalita Mahatripura Sundari. But, several other deities are also worshipped in the traditions as limbs of the main worship. There is something called Krama or succession of worship.
One of the important scripture about Sri Vidya is Parasurama Kalpa Sutra. The book Nityotsava elucidates it, so while the former is terse and short the later is much more detailed. Nityotsava has all the details about Sri Vidya that one needs to know specially about the rituals.
I am using Nityotsava as the reference here. It gives the Kramas in details and from them you'll understand which deities are worshipped in the Sri Vidya tradition.
Chapter 1 is called Diksha Krama. Various rules and rituals related to initiation are laid down here.
Chapter 2 is called Ganapaty Krama. It details the worship of Ganapaty, how to draw his Yantra, and every other details related to his worship and Homa as part of Sri Vidya.
Chapter 3 is called Shri Krama. It has the details regarding how to draw Sri Yantra, how to do Prana Pratishtha, what are the Guru Paramaparas of Hadi, Kadi and other Sri Vidya traditions about nyasas and a lot of other relevant things.
Chapter 4 is called Shyama Krama. Here, worship of Shyamala or Matangi is detailed. How to draw her Yantra, how to do Homa and purascharana of her mantra are detailed here.
Chapter 5 is called Dandini Krama. Dandini refers to Goddess Varahi. Here, we have all the details regarding the Goddess and her worship.
Chapter 6 (the last chapter of the book) is called Para Paddhati. In Parashurama Kalpa Sutra, the corresponding chapter is called Para Krama.This chapter has more details about Para or Goddess Lalita and her worship. It also has good amount of details about worship of any deity in general.
So, judging by these details, Ganapaty, Matangi and Varahi are widely worshipped in Sri Vidya traditions but not Narasimha.