Thank you for your reply.
i think it will be better to choose material in the widget, because we can easily apply that script for more painting in the future. For each painting could be their own widget with different material. We think about the specific need for material as u asked for, we plan that material will always contain one “base” texture - empty old paper texture, and second painting progress we can create material with two texture and param - alpha to cover each layer, we already create that material for each phase of painting, so in final u will have Bp contain two widget (slider - switch between years - every year different texture, slider - opacity of material - 2 texture with alpha channel) and model (model is same for every year, didnt change. We dont need any transitions between material change just normal swap. Every year is just one texture to change, not more, so every year has his own one texture(material).
Thank you so much for helping me with this.
Best.
C.