I have a realty client. They utilize a 3rd party listings company. Every day, they add/edit/delete listings via the 3rd party company. They want to import this data into their new BC site. They want to import and add custom fields and when they import each day, they want the standard fields to update (i.e. price) but the custom fields to remain untouched. The 3rd party can provide a tab-delimited file or they can ftp a RETS (Real Estate Transaction Standard) feed.