The old DesignSpark Mechanical forum where I posted quiet a few "Tips and Tricks" has completely disappeared.
It seems that this company doesn't care of their customers and have no respect to the people that contributed there, which is a BIG SHAME !
Because of such an inacceptable attitude, I won't write anymore tutorials about DS Mechanical and invite you to use other softwares.
I will let you know which other alternatives you have.

In SketchUp you can make groups and components.
The main difference between those 2 entities is that if you have several instances of a component its geometry will only be defined once which reduces the file size and memory usage. The other big advantage it has on groups is that you may change all components instances by just modifying one of them.

DS Mechanical also seems to have a component system which allow the same : modifying one instance will modify all the other components of the scene accordingly.

So it seems to be nice so far.

BUT the strange thing is that DS seems to ignore either it is a SU component or a SU group. In fact two SU groups with a same name will be seen as DS components. Therefore making a modification on one of the SU group in DS will also affect the other one... This is not what I expected.

And it's exactly the same with two SU components with a same name. They will also be seen as components in DS.
But not allways... And that's where things are becoming a bit confusing !

If you make a component in SU and duplicate it, both will be instances of the same component in DS and that is expected.
But if you mirror ("Flip along" an axis) one of the components in SU before importing your scene in DS, they will both become 2 different entities and will loose the component property. If your original components are both named "Anar" in SU they will be named "Anar" and "Anar_mirror" in DS and you won't be able to modify one and expect the other one to do the same.

Now if you do the same test with two groups both named "Anar" in SU, with one of them being mirrored from the previous, they will be considered as components in DS and modifying one will also modify the other.
So it seems that groups with the same name might be a better choice if you plan to manage them as components in DS.

If that was the only "problem" everything would be fine and we could just work with groups.

But there is also another problem that occurs on mirrored groups with the same name (but not on components).
When they are imported into DS, one of the group won't be at the right coordinates.
It seems that DS doesn't deal well with mirrored geometry...
And the result will also be the same if you scale by -1 instead of use the "Flip along" command.

So whatever you will choose, groups or components, you will probably get problems in DS if you give them a same name.
And if you give them different names then you will loose the power of components in DS.

It's a vicious cercle an it seems there is no solution !

The SketchUp scene

The same scene in DesignSpark Mechanical

Mirrored group exploded and remade as group

SU groups have been replaced by SU components