Apologies for being a little vague.....
I have been exploring marketpress and was happy with the setting that allowed for a 'global' showcase of sites on my multisite network.
I was able to search globally for products and display them within the Main site.
However, after playing around, I seem to have lost this ability and my main site/store front now seem to functioning as if it were on it's own.
Please could you use all of your powers of insight, deduction and a little mind reading to help me work out what I have changed to cause this.