Swami Desikan is said to be the incarnation of Gantai, the divine bell. Can we use the divine bell during padhukaradhanam of successive Acharyas (after Swami Desikan)?

The divine bell is a nithyasuri who is present in Srivaikuntham. It was present even before the advent of Swami Desikan. The divine bell is used during Tiruvaradhanam of Perumal and also for Acarya-s Tiruvaradhanam.
In certain places during Acharya padhukaradhanam gantai is not used so clarify before doing so.