Update one trace in a figure

I have a figure with a huge scatter plot (17 k points) and the skeleton of a model (6 lines, 7 points per line) like this :

I have an input form for the parameters of the model. There’s also an algorithm that improves the fitness of the model, given that you give it good enough initial values (parameters on the image are initial guesses, to further be fit).

Now, the scatter will not move through the process (long), never. It’s true observed data. What will move is the model and all 6 of its branches. And the projection of it on another figure (on-request).

What I have now is a validation button on the form to update the whole figure , but I only need to update the 6 model traces (42 points, very light). Is this possible to update only a few traces ? If this is possible, the next step would be to update the 6 traces with a client-side callback on the form parameter inputs (i/o of a validation button).

I believe that should be possible via the extendData property,

found this

exactly what I need
just need to learn js now …

You don’t need to use a clientside callback to target the extendData property, but it will of course be more efficient assuming that the data are present client side.