How to scale multiple anchors proportionally without moving other anchors in one path.

mysysctrim,

How about this slight elaboration on 3) and 4) in the first suggestion by Peter, Smart Guides being your friends:

1) ShiftClick on (rather than ClickDrag over) the desired Anchor Points with the Direct Selection Tool (same); this may go wrong unless done with care, especially with the Direct Selection Tool; make sure only the desired Anchor Points are selected, you can ShiftClick each of them to make sure;

2) Activate the Scale Tool (same);

3) Keep the Reference Point (so the selected Anchor Points form a shape that keeps its proportions when performing 4));

4) ClickDrag one of the selected Anchor Points directly towards/away from from the Reference Point, so it moves along the line that says uniform? You can hold Alt/Option to retain the original for trying a number of times for comparison and testing, also with the way described below.

Or leave out 2) and 3) and just use Object>Transform>Scale>Uniform if you know the % change; you can click Copy to retain the original for trying a number of times for comparison and testing, also with the way described above.

Sorry, I have tried this before I posted, this direct selection tool is only working when you drag them from one direction to the other, it won't allow you to drag multiple anchors from outside to inside center in specific parameters, so does the Transform option, it will transform the entire path which includes other anchors that deselected, not the anchors that I selected.