Can half an ellipse be locked to a reference plane?

[robinhillrhca700396]

Trying to create a symbolic washbasin that will flex a half ellipse.

I have set up reference planes to flex to the dimensions I need.
When it comes to locking the ellipse to the reference plane align command doesnt work for an ellipe minor axis.
Drawing without locking the minor axis to the reference plane doesnt flex as can be seen in the attached file (half ellipse was drawn to the front reference plane before flexing).
As its elliptical I can't set up a radial dimension to control the ellipse.

Can anyone guide me as to how to lock the ellipse minor axis to the reference plane or otherwise parametrically control the partial ellipse?

Thanks, Robin

[duende.anisotropico]

ellipse.jpg

Try this....

[robinhillrhca700396]

Many Thanks,
using a dimension of zero to tie to the reference line does the trick.
Robin