Shortcut for an object with parts not distorting after resizing, and perfectly aligns with its edges

The behaviour you are describing is quite normal because the edges of the bars do not abut as it would be required in this case.

It actually does work with art brushes and symbol instances. It is just important that their bounding boxes (edges) precisely touch each other horizontally. It's a slightly different appearance, but that should be acceptable.

See this sample .ai file.

Art Brush and Symbol Scaling

It contains two groups with art brushes and symbol instances. If you select all and scale horizontally 1000 % (while Scale Strokes and Effects is turned off), you can see that the bars are still aligned accurately.

Why can't you align the symbol instances? It shouldn't be a problem with Smart Guides turned on.

What happens with symbols is that live text gets distorted. This can be solved with the Outline Object effect applied to them.

Then arrange your objects and group them and then apply a rectangle effect to the group. In order to perfectly align the rectangle, the rectangle effect must be followed by an Offset path effect that shifts the stroke inwards by half of its weight.

Z,

Possibly far too far out/silly/simple, but based upon the assumption that in all cases the A-BLUE-A (the A part including the yellow and the black frame round the A) and the B-RED-B (the B part including the yellow and the black frame round the B) are to be stretched by the same amount/proportion, but only the BLUE and the RED are stretched whereas the A parts and the B parts are to be kept unstretched:

How about this?

1) With the GREEN as a common background, Group the/each A-BLUE-A instance, and Group the/eachB-RED-B instance;

Keep the GREEN background unlocked, and:

2) Lock (all) the Group(s) except the leftmost one, then ClickDrag over the entirety of the leftmost A part along with the leftmost parts of the GREEN and the BLUE to select all Anchor Points of the A part as well as the leftmost Anchor Points of the GREEN and the BLUE (avoiding to ClickDrag over the rightmost A part); then Object>Transform>Move and insert the negative X value that gives the desired stretch of the whole Group (and the correspond part of the GREEN background), such as the current width if you wish to double it;

If/as long as you have more than two Groups as in Object 2 and Object 3, contimue with the following:

3) Unlock the next Group to the right and repeat 2), only ClickDragging over the unlocked Groups (avoiding to ClickDrag over the rightmost A/B part) and apply the same Move;

When you have reached the middle, reverse 2) and 3) working from right to left and using the same Move, only positive.

Hi

You could try this approach, maybe:

1. Create a group of A and B.
2. Add a new fill to the group and move it beneath the contents. Give the new fill the colour of your choosing.
3. Add another fill, move it to the bottom of the stack, and apply an offset path effect to give the stroked appearance desired.
4. Repeat for the second A/B group
5. Group both A/B groups into a larger parent group and add a new fill to that—again, move this to the bottom of the stack—and then using the Group Selection Tool or Isolation Mode, you should be able to move everything as desired and the appearances will do the bulk of the work.

Hope that helps and if I get chance today, I'll add a video showing this process.