To place 1 object on top of another in Bambu Slicer, you have to make them an assembly. This is very easy to do. He are the steps.
- Click the first object to select it.
- Hold Ctrl and click the second object to also select it.
- With both objects now selected, Right click and choose Assemble.
Now if you go to the left side of the screen and switch from global settings to object settings (The word Global appears in green by default, simply click the word objects next to that).
You should now see your assembly on the left with the individual parts of the assembly listed below it.
Just select the part on the left that you want to raise and once it is selected you can move it up or down as you normally would and it will stay. Hope this helps.