Next time, you can give cuttings. With a little root propagator (or willow sap I've heard), you can make some plantlings to share. I got a rosemary cutting from a neighbor, and it's doing great with just spring water and sun. Most herbs can be propagated from cuttings especially the ones that spread (rhizome monsters).
Oregano is pretty invasive so the trim back was probably a good idea. Too bad it had to happen in a tougher season.
How're your MIL's plants?