CASTING URSULA IN FUTURE DESCENDANTS MOVIES

We know Whoopi Goldberg voiced Uma's deadbeat mom in Descendants 2 and we only saw her tentacle. In Descendants 3 she was never mentioned at all, until in the next movie Descendants 4 and that we are already introduced to her sister Uliana, which is very bizarre since we never saw Ursula yet we see her sister who looks identical to Uma. Most Descendants fans are so anxious to see the sea witch in the next Descendants movie. Who do you think could play Ursula?