Groups

[merc]

Hope I am in the right section.
I drew a ramp for my trailer. Then I highlighted a bunch of lines and created a group.
When I rotated the group some lines that were supposzed to be part of the group stayed. I must have missed them when cfreating the group. Conversly, lines that were not intended became part of the gtoup and moved with the rotation. Again I must have highlighted lines I didn't mean to when making the group,
How can I now add the lines to the group that stayed behind and make the unintended lines no longer part of the group?
Sorry for the long post.

[TIG]

Select the edges you wanted to add into the group but accidentally missed.
Use Edit > Copy them.
IF any of them are needed to maintain faces in their original context then I suggest you 'Copy' this rather than Edit > Cut which will delete the face as the edges as clipped out...
Edit the group with these edges should have been.
Use Edit > PasteInPlace.
The edges are now reproduces inside the group.
You said you had rotated things... apply the same rotation to these newly added edges.
IF these newly added edges interfere with geometry in their new home and might then skew geometry they have stuck to, you can avoid that - as soon as you PasteInPlace them make a group of those highlighted edges, so they are in a temporary group inside the main group. Then apply the rotation to that temporary group, re-snap that group to where it should be relative to the existing lines if that's needed.
Explode the temporary group so these recently added edges merge into the group's geometry.
Tidy up by erasing any unneeded edges that are still left outside of the group...

[Dave R]

Going forward, I think it would be a good idea to make sure you create a group or component of the geometry you've drawn before moving on to the next part of the model. This way you can prevent the problem you've experienced from even happening. Be systematic in your drawing. If you are drawing a trailer and then the ramp, make sure the trailer is a group or component before you start drawing the ramp. Or if you are drawing the individual parts of the ramp, draw one part and make it a group or component before moving on to the next part. Use components at least for parts that will have multiple instances or that you want to save for reuse.