Question on name lookup from web form

Hi All,

My client is asking for this:

There is a field on the form called “PrimaryContact”. When someone changes this field or creates a new document and enters a name in the field - they want to look through a list and match the last name to see if it already exist.

A couple of issues I see with this since there is not a contact form now. I would just be looking at that field n a view for comparison. I thought about creating a Contact form and having them create a list of names and select the name from this area.

So my questions are these:

  1. Whats the best way to do this?

  2. How on the web when someone exits a field do a lookup and prompt them if you find a match on the last name and ask them is this the same person and if it is, update a field on the form that he is associated with another firm as well.

I hope this made some kind of sense.

thanks in advance. LS