Dynamic Drop Down List Variation

Hi,

I've been scratching my head, seen other threads and trying to work out how to do this, but for the life of me I'm stumped!
The background:
Basically I have a list of well over 1000 people linked to diferent companies in one table, and in another table a list of all the different jobs a person can do for a company which is about 800 long.

In this list of 1000 people and companies it actually works out that there are about 300 people, but they are able to work for different companies. And in doing so can also do different jobs for said company: eg John could work for Company A as a Skill1 and a Skill2 and so needs to have two entries.

The list of 1000 people is every changing and can increase (or decrease, but that's unlikely).

The Problem:
With these two lists i'm entering this into another table. This table uses data validation. First for the Name and ref number of the people and then for the company and skill. What I'm after is depending on the person selected in column one, the drop down will only show the companies and skill that person has a relationship with. I've attached an example to try and show what I'm after. So using that, if John were selected in column 1 then he should only see the company and skills for Company A and Company C, reducing the list in the drop down.

I hope someone understands this, cos I'm baffled with indirects and substitutes!

Thanks in advance...