@derekagorhom this is another task mainly for @Raymond-Andam . I hope it can be done in parallel with his other work. I am keen for developers to have multiple tasks, because they may have to wait for help, or testing on each one.

This should initially be easier than some of the tasks on #8789.

Here is the current scatterplot dialog:

a) Could you make a group box with label Add. That is round the current Add Line of Best Fit, and Add Rug Plot
b) In each of those please delete the word Add. It doesn't have to be repeated.
c) Add another checkbox with label Side Plot. For now it can be disabled.
d) Decrease the vertical space slightly between the 3 options in the group box labelled Geoms. Also delete the s, so it is Geom.
e) Make that group box wider. Then, in the Point row, add a checkbox before Size and another before Shape. Default is unchecked, and then the up-down and drop down controls are hidden.
f) Similarly add checkboxes for the Count. Make the first one now Colour instead of Legend, because we have added legend to the bottom of the dialog. Use the same control and options for Colour from the sub-dialog.
g) Change the R code generated slightly. I think it now gives you the size, etc inside the geom_point(), and they should now only be set when the checkbox is ticked. (The reason is that it is also possible to have a size and/or a shape aesthetic i.e. a variable). If size and/or shape are given as a single value inside geom_point, then it will ignore the aesthetic.

That's all for you now, but I have a question for @lilyclements .

I am very keen to be able to add marginal plots to the scatterplots.

I think they are useful anyway and partly for teaching. The popular way most people seem to use is with ggExtra, asa shown above. It is simple and nice and powerful, but has 2 defects to me anyway.
a) It is a slightly different syntax.
b) It seems not to cope with facetted plots.
A more recent package is ggside. It will be a bit more complicated to add to the dialog, but I think it looks great. Do you agree?