I think you may be misunderstanding what causes the child parts to become "updated".
There is no need to edit the split command.
In order for the changes to propagate to the child, the following needs to happen:
The parent part must be open in SW
The child part must be rebuilt
So, if you have all three parts open (one parent and three children), ...
Well the main problem is that a B-Rep model can not end up producing nonmanifold edges. The thing is a laser obviously has a kerf and your CAD application is intended to model the end result after cutting. Even a cut without a Kerf would produce a cavity with 4 sides. Obviously optimization like this is the CAM modules job.*
But if you must like to suggest ...
A "bonded contact" is presumably the same as welding the parts together.
Presumably, the material also has non-zero Poisson's ratio.
A friction coefficient of 0.01 will allow the ends of the pin to expand radially as it is compressed. The small but non-zero friction coefficient will stop the compressed pin from being perfectly cylindrical as it ...
Misumi, a configurable components vendor, has a plugin that allows you to directly insert Aluminum extrusions from their catalog into solidworks: https://us.misumi-ec.com/service/promotion/rapiddesign/
You will have to use their extrusions, but that will most likely be the case for any plugin that functions similarly.
Placeholder answer - I've made the model, but don't have time to write up how I did it just now! :)
In short - make a plane, use intersection curve to make your sweep path. The, if you want to keep normal constant, make another path to use as a guide curve.