Nested blocks?

I have an html table, which content is the result of a query, so I use a block to render it. (the data is put in an array, let's call it AA)

I want one of the column to be a combo box with the content of a db table (unfiltered, the data is in another array, let's call it BB), where I make "selected" the "option" with the same value in AA for the AA record of the row.

To do this, I need a nested block, but it does not seem to me really a sub block (the content of BB is the same for every AA record).

Some suggestion?

I think there is no need to have a sub block.
You simply have to merge BB first, then AA. So BB will be repeated for each row of AA.

For selecting the correct items in the combo-boxes, I can use 2 technical:
First is a dedicated plugins: http://www.tinybutstrong.com/plugins.php?help#plugin_html
The second is using JavaScript.