Both!
Srimath Ramanujacharya is our uththaraga-acharya; he is the one who pulls us out of this samsaa sagaram.
The acharyan who gave us pancasamskaram is the upakaraka-acharyan; he is the one who connects us to Ramanuja-thiruvadi.
We all are supposed to do திருமேனி கைங்கர்யம் and all kinds of other services to our upakaraka-acharyan. After he has attained திருநாடு, his successor takes up the responsibility of engaging us in services which are essential for our well-being. He also prays for our well-being (unwavering connection, ever increasing attachment and deep involvement in kainkaryam to Ramanuja-thiruvadi) everyday during this daily திருவாராதனம். (please listen ~7 minutes of Enpani 864 https://www.kinchit.org/kinchit-en-pani/851-900/). Just like our upakaraka acharya represents Ramanujacharya, the current acharya represents our upakaraka acharya.
Thus the current acharyan represents previous acharyan in all capacities.
adiyen dasan.