Edit shape programmatically (add attribute to textblock or replace whole textblock within shape)

Hello guys,

we have some (2000+) shapes within we need to edit (add) attributes (Part Of).

These shapes contains textblocks with:
Associated Function
Associated Location
Designation

We need to add Part Of attribute as well.

Question 1: Can we add this system attribute to shape programmaticaly?

Since Part Of is system attribute and has no ID or something, we decided that maybe we can create new textblock stencil with all 4 attributes and try to replace those textblocks in shapes only.

Question 1: Is there any way to edit shape itself and replace these textblocks programmaticaly?

Thank you,
Tomas