receiver of my mod box resets group but it reverts if taken back into her inventory

[Starlight Harbour]

I am trying to send a modifiable box with a no-mod script inside it to another user and cannot get  the hoped for result. What I was

hoping for is that the recipient could modify the box but not the script.  Sadly that is not what happens.

What happens is that the user receives the box, and upon opening it, it shows the MOD box checked, and even says "You can modify this object". Good.

And, indeed,  the user can change the texture of the box, save it to inventory, re-rez it and the texture survives unchanged.   Still good.

BUT,  when the user changes the GROUP the box belongs to,   with the box rezzed,  they can do it and it seems to work.   But as soon as they take the

box back into inventory three things happen.  (1) where it used to say, in inventory (no copy) it now says (no copy) (no modify) and
(2) when they rez it again,   the GROUP reverts to what it was when I sent out the  box, and (3) curiously, the texture does not revert.

 I looked for any further posts here regarding permissions.

I found and  read with interest the Oct 14 thread

Of course I found the overall result of that problem to be basically:  "Second Life does that sometimes".

I imagine this is relatively easy for someone else to replicate on some different sim, with

different avatars and different box, on a different day if any of that changes things.

Advice?   Links to the best place on-line to read up on permissions?

Links to other discussion forums where I might find assistance such as StackOverflow with tag [lsl-script]?

Thank you.

Afterthought #1 -- Yes I did set modify BOTH with the box Rezzed and with it in inventory.

Afterthought #2 -- BTW,  the right tag on StackOverflow seems to be [linden -scripting-language],  "right" in the sense that it does pull up 58 posts (in all time), but the group seems to be just barely alive. 

Edited December 8, 2019 by Starlight Harbour
adding afterthought #2 - info found on StackOverflow