What does Siya mean?
A regional and poetic short form of सीता (Sītā), the heroine of the Ramayana, whose name means 'furrow' (she was found in a ploughed field). Siya is widely used in Hindi devotional usage (as in 'Siya-Ram').
What does Aadhya mean?
From Sanskrit adya (आद्या), feminine 'first, primordial, the beginning'; used as an epithet of the primordial Goddess (Adi Shakti / Durga).