Adiyen a Srivaishnava who does not belong to the Brahmin community; our family deity is Thiruvallur Veeragahava Perumal. My grandfather did his embossing of mudras at Sriperumbudur and he lived a life of a Srivaishanava in his village. The tradition stopped with him. We only visit the temple during festival time and became unaware of our tradition. Adiyen desires to lead a life of a Srivaishnava like my grandfather, but we do not know who our Acharyan is and how to proceed in following the Srivaishnava way of life. Should adiyen also do sandhyavandanam and other rituals as well?

As you are not aware of your grandfather’s Acharyan, you can seek any Acharyan of your preference.
If you feel that a particular Acharyan will transform you, you shall seek Him and pray to Him for Samashrayanam and Bharanyasam.
Many preceptors, starting from Ahobila Mutt and so forth. Whomever that you are devoted to, you can submit your request to that Preceptor.
Notes
Kshatriyas and Vaishyas are ordained to do sandhyavandanam like Brahmins and it is not ordained for the rest. One can take bath and apply the dwadasa urdva pundram and worship the Acarya thaniyan in the morning and continue to do other routines.