Not sure what you mean by "irregular shape/opening". Looks pretty conventional to me. Are you meaning that there is no host for the Railing? If so, why not create a "reference" host and hide it in the View?
...this might be of interest to you as well:
But I don't see there is an option of railing for curtain panel. Railing is different system family. It seems not to allow me to edit the family.
@hliS658H wrote:
But I don't see there is an option of railing for curtain panel. Railing is different system family. It seems not to allow me to edit the family.
Create a curtain wall type that is the same as your railing type using mullions as rails and balusters.
The highlighted two parts will be hard to use height correction. Otherwise this is a good way to model it. Curtain wall method is more straightforward. I am able to make it. Thank you!
Is there a way to add top and base like this? I tried to add Horizontal Mullion, it was just horizontal and not following the profile.
Very strange thing happens - the horizontal border has been separated to small segments by the railings, but the border looks fine along the slope.