Hi a.l.e.,
Inkscape it is--and thanks for the tip on importing it as a .svg. I want to pass on something I did learn concerning concentricity that might be useful. I had not tried your suggestion to ctrl-click to test it to see if you could ctrl-shift-click to link the shapes and thus combine them.
To try shapes other than just target circles as in the tutorial mentioned above; as an experiment, I created a smaller rectangle, say 2 x 4, and used the "round corners" dialog to create a capsule or pill shape. No matter which Transform I used from dialog box using the centerpoint box and equal scaling values (hidden behind the Add button) would I get a correct percent transform, up or down. The rounded ends accepted the correct proportional increase or decrease, however the straight sides did not accept the proportionate change. (In my case they split the percent in half and applied that to each side.) And to boot, the innermost one lost it's frame and was not Shift-Selectable to use the Path Tools, but the inner shape itself remained visible.
A method that finally linked the two capsules into one shape was for me to create a bigger capsule FIRST, then creating a new shape frame inside that one to create a proportionally smaller capsule inside the larger one. Once the smaller capsule was constructed but with it's frame still visible (active) I Shift-Selected it and then Shift-Selected the larger one outside the smaller one's frame. Both shapes and their frames stayed visible and Item > Path Tools > Combine Polygons became a selectable option. They combined fine. I do not know if this method would work with more than two shapes starting from the smallest one up, somebody's frame might disappear.
The contained (smaller) shape did not have to be the same or concentric, so long as the smaller shape's frame remained active and selected before shift-selecting the larger one's frame. Otherwise the smaller one's frame disappears inside the larger frame and is not selectable.
Just for fun: I threw out my original logo idea and took my linked capsules, stood them on their head, and made a nice Egyptian Cartouche (see attached).
Thanks,