Multiple Category Filter Widget

We are trying to find a way to filter widget content by multiple categories and struggling!

Here is what we are trying achieve…

Each post can be categorized in the following way…

1. One offering type (advice, product or services)
2. Multiple focus areas (property, employment, financial, etc)

One the right hand side of each post page we have three widgets showing related posts, one for each of the three offering types (advice, product or services) specified above.

What we are trying to do is filter the posts by offering type so they go into one of the offering type widgets and then by any of the focus areas which relate to the post being displayed.

So a post about ’employment’ would display all related posts that relate to ’employment’ in the right hand widgets but they would be split according to the offering types they are categorized as.

Any ideas?

Thanks!