The smoother in graph builder is a subic spline with a lambda of 0.05. If that works for your situation, then your plot could create a seperate smoother line for each grouping in graph builder by overlaying a column whose values correpsond to the groupings you want the points/smoothers divided into.
If you want to stay with a bivariate plot, you can also do the same thing using the "group by" option where you would select a column whose values correspond to the groupings.