Can I convert jam into chutney? I made a rhubarb jam a little while ago, basically rhubarb, sugar and grated ginger.  Its quite gingery.  

I've now made some duck terrine and fancy serving it with some chutney.  I have some chutney, but I wouldn't mind trying to convert some of my rhubarb jam into a rhubarb chutney, to use tonight.  

Not really sure how I might go about this, but was thinking I might soften some onions and garlic, then mix these and some cider vinegar into some of the jam.

Is this likely to work?  Anyone got any better ideas?  Would it be different if I had more time?
Perfect idea and great multi-use of your jam!  Your plan is perfect...just create a nice sweet tart balance to your liking.  If you want a little more texture you could plump up some golden or dark raisins by nuking them in the microwave before adding.  Coriander seed is often used and provides a little texture contrast as well.  A bit of ground allspice could be good as well.