Bad idea indeed. Or in fact you have a logical error, in form do and don't do at the same time. Now the real question is what are you really after when your are freezing (what is the service you think freeze does for you). I find people have mystified freezing to the utmost end. My advice to everybody is:
Do NOT FREEZE unless you have a MATHEMATICAL BENEFIT of doing so. This incidentally means unless you know what the mathematics behind freezing and the thing you do after freezing does is don't freeze.
Freeze is super simple stuff (its about as complex as addition in this example). imagine object B under transform A with point P (or many points P1, P2 ... PN actually but showing one is enough), see ASCII picture below.
X ^ P X
^ | (2,5)
| B +->Y
A +->Y (1,9)
Now here A is in origin (world space) B is located in A's space at 1,9. NOTE these cord syses are NOT the pivot point, they are the origin of the object, the mathematical center where things are calculate from. Now the point P is measure relatively form B what freeze does is it moves B so it coincides with A and moves the position of each point P so they APPEAR to have not moved at all. Ala:
X P X
This works and does something useful for many things, and something destructive for others. Now your situation (something like this anyway does not matter if B and C are under different mothers) is:
X ^ P X ^ P X
^ | (2,5) | (2,5)
| B +->Y C +->Y
A +->Y (1,9) (1,28)
This does not work. Because the question is if i move B and C to a what number do i put to P so that it stays put. Remember P is the same number all over, its shared. This would work if P was not the same in both cases but since its instanced you would need P to be (3,14) and (3,33) at the same time which is not possible.
So either you don't instance the stuff and freeze OR you instance and don't freeze. Those are the options. So now is your question how to UNINSTANTIATE a shape? Check your duplicat options, then duplicat again without instancing and dlete the extra instance!
- *maya separtes that form where the things are measured from to save time in calculation should you move the pivot, so instead of updating 3 * nim vertice values maya updates 3 values. It saves time and is more accurate.