Do you have any idea to trim/hide the blocks automatically when overlapping with another blocks?

That sounds like something only a custom lisp routine "might" be able to handle.  Only someone familiar with lisp could give you an exact answer.

I also think so, but may be need some c++ expert. I don't think it will be possible with only lisp.. don't know may be....

Good luck with that.

If you wanted only one of them to have part of its boundary disappear, you could build the Block with Wipeouts in it, and control which one wipes out the other with their Draworder.  But that would also wipe out the hatching of the Block that's behind, which isn't in accordance with your image.  And they couldn't mutually wipe out each other's edges by any means I can think of, as Block insertions.  You may be stuck with Exploding them and Trimming pieces out.

Yes, it is okay if we wipeout any specific area. Actually wipeout hides the other objects below the block.It is also okay if we built the block like that without adding the wipe out.I need some program which will automatically clip that overlapping portion of the block.For now I am doing manually with "xclip" command. "xclipframe" command to turn ON/OFF the boundary.