Dynamic boxing of a block with attributes

Hello forum,

I have been searching far and wide for this and found nothing that exactly does it.

Attached is a block, this block contains some attributes: Name, Family name, Phone and a reference number. Theses four are enclosed in a box with an associative solid hatch at 25% visibility in the backgroud.

As of right now, it's a dynamic block with a stretch action that is used to make a bigger box for enclosing bigger attributes (A name with 15 characters, for exemple). So, it implies doing it manually every time, for every blocks and whenever I redefine the block.

What I want it to do, obviously, is to automaticly detect the longest attribute between the four and ajust the box to the new size without user intervention.

All the commands or LISP I found have failed me, they all works wonders with MTEXT but not with attributes.

Is it possible to do it within the block or does it have to be done in the drawing after being inserted?

Thank you,

BLOC_POSTE.dwg

Would creating some constraints work? I'm not sure you can base it on text/attributes, I know it would work for a line length.