I think one definitely would have faced this problem while integratiing many instances/blocks in the top level layout in Virtuso.
The problem I am facing is as follows:-
In the top level of the layout, I have to integrate many instances of layout blocks.
While connecting two blocks ( these two blocks are inside a bigger blocks (like PAD array) or may be crossing over another small block) , some how some the other blocksare getting moved.
Ideally like to keep the positions of other instances ( let's say A, B, C) fixed, while editing the desired instances ( let's say E,F) as movable.
I tried in LSW. I dehighlighted the 'inst'. In that process, all the instances are becoming un-movable. Even if you bring a VIA , you can't move it around.
Could anybody please tell what I should do thing smoothly.
In IC615 (you didn't say which version you are using, and it's rather useful to know...) you can use Edit->Select->Set Selection Protection to "protect" a number of shapes/instances. This will make those objects unselectable (you can highlight them from the same menu, or temporarily override the protection, or remove the protection). That means you won't be able to accidentally select them and hence not be able to move them.
In earlier releases, you can use my SKILL code as described in this article on Cadence Online Support to do the same thing.
If you're using VLS XL you can also use the constraint manager to add a "locked" constraint on the instance to stop you being able to move it when in Constraint Aware Editing mode. Could also use a "fixed" constraint.
In IC5141 it's also possible using Virtuoso Layout XL - you have to use Tools->Constraint Manager in the CIW, and then you can add a "fixed" constraint for some instance. You have to turn on "Constraint Assisted Move and Stretch" in the Layout XL Options form too.