ICAS received support this week, from the Indian and Australian institutes, in its fight to preserve its name.
The institutes have backed ICAS's insistence that there is an "unbroken global convention that chartered institutes use their geographical designation".
ICAS has already lodged its objections with the Privy Council, and has not ruled out legal action.
Des Hudson, ICAS chief executive, said:
"It is now very clear that this proposal from ICAEW is demonstrably unpopular across the world's chartered accountancy institutes. The argument in opposition to the change is totally consistent from ICAS, our Australian colleagues and now our Indian colleagues."