All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
As explained in the mentioned Fatwa, both acts are permissible, however, it is better to move the finger sometimes and to leave moving it other times. Doing both acts in the same prayer is permissible, and not obligatory, and you may also do one of the two acts in a prayer and the other in another prayer, but without always abiding by the order you mentioned in your question, i.e. one act for the first Tashahhud and another for the last Tashahhud.
Allaah Knows best.