no, I dont want them to be erased totally.
I just want part of sprite to appear in the main screen and not in the other split screen below!!
setup a raster interrupt to happen at the same line as your screen split.
Now disable the sprites. Either write the mag value that turns them off, OR write a X or Y value that moves them to a position that is not seen (e.g. a previous Y value such as 0 - this would work because your panel is say, at line 200, and you can't display the sprites here if they are at line 0).
Then after the panel, another interrupt to either reset the mag, or to set their correct positions.
Setting mag is faster and easier than setting X or Y position.
I assume your screen split is using plus screen split and not crtc classic split?
if you used a crtc classic split the sprites would automatically repeat in the panel if they were near the top of the main screen, this is because sprite coordinates are computed from crtc values.
This will work and the sprites will appear to be cut by the panel.
EDIT: Attached source for an example that does exactly this.
It shows:
1. screen split
2. sprites cut using mag
You can see how the sprites are cut, and then later you can see them enabled again (this happens because I disable where split is - but this needs to be tweaked to make it accurate and hide in the border for example), and my later int to re-enable them again happens just after the panel at the bottom so you can see it enabling them again.