I know that one can plot circles in stata using a weighted scatterplot. Is it possible to plot ovals, or ellipses along the same lines? (I.e., longer in one dimension than the other).

Background: I'm running a differences in differences model where I'm allowing the treatment effect to vary by groups, with around 10 groups total. I have two different outcomes and run two separate regressions, resulting in two sets of coefficients. I have been making a graph where I plot the group treatment effects on each outcome as a scatterplot (i.e., each point is a group, Y-axis is the treatment effect in that group for outcome 1, X axis is the treatment effect of the group on outcome 2). I'd like to try adding confidence intervals in the form of an oval around each point, where the vertical diameter is the 95% confidence interval for one outcome's treatment effect, and the horizontal diameter is the 95% confidence interval for the other.

(For the record, I realize that (a) this may be illegible, and (b) this isn't really statistically accurate, since to plot a true "confidence area" you'd have to know something about the covariance between the coefficients in the two separate regressions. Still, I'd like to know if it's even possible, so please humor me )