I'm having similar issue with circular pattern (not in macro environment, just a sketch):
it seems it's a problem with circular pattern feature itself (since 2007 at least), as I cannot find any way to fix the center. I'm in contact with my VAR just now about this...
The only workaroud I found is to pattern with angular dimension only checked, then to drag the center away and then back over the origin; in this way the point get fixed.
No idea how you could do this with API...
If I get any news from my VAR I'll update you
just FYI, my VAR found no way to fix pattern center point.
The only workaroud he suggested is:
1. pattern around a point different than origin (let's say around (1,1)) with just "equal spacing" checked
2. select (1,1) and PART origin (from the feature tree)
3. set a coincident constraint between them
It should be quite easy to follow such a workflow also in macro (but I'm absolutely not an expert in macro...)
Sorry, no other idea.
Thanks a lot.
I will do this suggestion..
Have a nice weekend