Alix this is an absolute hoot.  It reminds me of a discussion I had with a now former client, who wanted me to do mortgage retrievals for $10+ costs.  So, ok, give me a book & page reference & I can retrieve anything you need - an easy, peasy $10; but no, actually, that wasn't what they really wanted.  Their brilliant idea was to give me a book & page reference & if it turned out that the mortgage had been discharged; then could I just look for whatever was outstanding & send that along with a schedule (run) sheet to them for the $10.00 fee.  I am actually laughing out loud as I type this.  They must have thought I was a prize idiot when they entertained the idea that I would be willing to do current owner rundowns for $10.00. 

 I am still a little unclear about what your client is actually asking for, but to me it sounds like they're asking you to provide a chain of title regarding o/s mortgages.  Will they then take the framework you provide & flesh it out with photocopies & a significantly larger bill to their client? 

 I would be concerned about liability if that was part of what was going on in the background.