# Insert Edge SubD not working with reflection plane

**URL:** <https://discourse.mcneel.com/t/insert-edge-subd-not-working-with-reflection-plane/202146>\
**Category:** SubD\
**Tags:** windows, reflection, mac, subd\
**Created:** [March 27, 2025, 3:50pm UTC](https://discourse.mcneel.com/t/insert-edge-subd-not-working-with-reflection-plane/202146 "2025-03-27T15:50:26Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Joshua\_The\_Jeweler](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/joshua_the_jeweler/32/632623_2.png) [@Joshua\_The\_Jeweler](https://discourse.mcneel.com/u/Joshua_The_Jeweler)\
**Post date:** [March 27, 2025, 3:50pm UTC](https://discourse.mcneel.com/t/insert-edge-subd-not-working-with-reflection-plane/202146/1 "2025-03-27T15:50:26Z")

</div>

I’ve been doing a lot of subd modeling recently and often like to use the reflection tool, however I find that when I turn on reflection it always reduces the sharpness near the reflection plane. Creasing does not work, and I don’t want it creased really. I tried the “insertedge” command to add an edge near the reflection plane. The preview displays correctly but when I hit enter the command fails. I tried inserting an edge in another area not adjacent to the reflection plane and the command fails still, so it appears this is not possible while reflection is active. Is this a bug or is there another way to accomplish this with reflection active?

Here is the shape after initiating the reflection plane

 ![Screenshot 2025-03-27 112733](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/4/e/7/4e716f747b64445a776e0caedbe856e975dd18b1.png)

This is the preview after activating the “insertedge” command

 ![Screenshot 2025-03-27 113059](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/0/0/3/003de8014c1980614de1a9eab85ff2e134639290.jpeg)

This is the command line showing the failure  
 ![Screenshot 2025-03-27 113130](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/d/f/6/df6a4046c1109d10b6447d4e8d693d04c90946a3.png)

Here’s the sample file  
[reflection issue.3dm](https://discourse.mcneel.com/uploads/short-url/bMQkxTGWdiMHU4qR0LP49DsR1wL.3dm) (161.9 KB)

---

<div class="post-metadata">

**Author:** ![BrianJ](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/brianj/32/751593_2.png) [@BrianJ](https://discourse.mcneel.com/u/BrianJ)\
**Post date:** [March 31, 2025, 8:17pm UTC](https://discourse.mcneel.com/t/insert-edge-subd-not-working-with-reflection-plane/202146/2 "2025-03-31T20:17:27Z")

</div>

Hi @Joshua_The_Jeweler ,

Make sure to place the point for the inserted edge on the parent side of the SubD when Reflect is active. You can move and transform the reflected (child) side of the SubD but to create geometry you’ll need to be on the parent side which is shaded lighter.

Also think about using Box mode for the SubD via the Tab key and then the Gumball scale handles with sub-objects selected or the Align command \> ToFitPlane to make faces planar with one another across the reflection plane. This will round out the form more if that’s what you’re after.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/6/6/a/66a1aae5f877ef11d7024a65816a0518380d1e5f.jpeg)

---

<div class="post-metadata">

**Author:** ![osuire](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/osuire/32/656689_2.png) [@osuire](https://discourse.mcneel.com/u/osuire)\
**Post date:** [July 22, 2026, 9:18am UTC](https://discourse.mcneel.com/t/insert-edge-subd-not-working-with-reflection-plane/202146/3 "2026-07-22T09:18:40Z")

</div>

The parent/child relationship is a hindrance.

It’s made even worse because point editing sometimes work on the child, in the sense that it affects the “parent”… and sometimes not.

Also, there is no visual cue as to which is which. Bad UI.

It would make sense to be able to edit any half we want since mathematically, it’s a bijection.