I've owned a few OM-10s. They're decent enough cameras, although I've never much cared for them -- mostly because they lack shutter speed control. But you can buy a manual shutter speed adapter for the OM-10, which I consider to be a necessity. Reason why is that I feel most strongly that anyone who is at all serious about photography should learn the principles behind it -- foremost being the "trinity" of shutter speed, aperture, and film ISO and how they interact with each other. With the manual shutter speed adapter for an OM-10, this relationship can be explored.
Also, keep in mind that, since you already own (or at least your sister does) a collection of Oly glass, you can always add to the stable of Oly cameras. A decent OM-1 or OM-2 can be a welcome edition, and either can usually be found for quite a reasonable price at sites like eBay.
I strongly encourage you to spend some time with SLRs that require you think about exposure, as opposed to P&S cameras that don't. But if you still want a P&S camera, there are so many to choose from, many of which are actually excellent picture takers, so it becomes difficult to suggest a particular model. I can only make recommendations based on my own experiences. I've used and can recommend the Canon AF35ML (aka "Super Sure Shot"), the Canon Sure Shot Classic 120, the Canon QL17 GIII (not really a P&S but more of a true rangefinder with limited auto functions), the clamshell Oly Stylus cameras (there have been many different models and I don't recall which model it was that I had), the Oly XA (again, more of a rangefinder than a P&S), and the Minolta Hi-Matic AF2 (from what I understand, all the Hi-Matics are very useful cameras, however).
Whichever route you choose, good shooting, and may all your images be keep-worthy.