Het there art community!

Im working with Mempathy using Unity , https://soygema.itch.io/mempathy

The scene progression is composed of blue-watercolored backgrounds. Now I have a transition in which the transition is as the image shows.

I would like to implement an effect of water dropping change, instead of being painted  ( as in we might be splitting water and the watercolour might be transformed into the next one ) 

• Do you know if this can be done painting alpha in a rendertarget ? or painting in mesh textures with Shaders?

Can someone pinpoint me towards the right direction?

thanks in advance for your help, it means a lot ! ^^