Do you have a backup of the "old store" ?

It might take a bit of digging, but this sounds like a customized function - and if you find it, there should not be a problem bringing it into your new upgrade.

One way to look for it is to COMPARE the old set of files with the CORE SOFTWARE of the same version. As this is likely to be an ADMIN function, start looking for differences in that area.

Use WINMERGE or BEYOND COMPARE to do bulk file comparisons.