Nesting Sitecore sublayouts/placeholders - possible?

Question

I have a Sublayout called TwoColumns that looks like this:

<div class="row">
    <div class="column span8"><sc:placeholder runat="server" key="left-column"></sc:placeholder></div>
    <div class="column span4"><sc:placeholder runat="server" key="right-column"></sc:placeholder></div>
</div>

I would usually add other sublayouts through my presentation details, and specify the placeholder as left-column or right-column.

Now, say I want the exact same proportion columns but WITHIN the left column. As such:

I could add the TwoColumns sublayout to the left-column... but if I want to add something to one of those nested placeholders, how do I do that? Is it possible to set "left-column left-column" as the placeholder?

What about if I want a second ROW of TwoColumns? How can I specify whether I want my content to go in the first row's left-column, or the Nth row's left-column? Is Sitecore even capable of this by default?

Please note "Just create a new sublayout called NestedTwo columns" is not the solution I'm looking for. I'd like a flexible grid system.

Don't worry about the CSS grid system, that is done. This is a purely Sitecore question.

Answer 1

This article is a really good start:

http://trueclarity.wordpress.com/2012/06/19/dynamic-placeholder-keys-in-sitecore/

With the above I can use the same sublayout (with the dynamic key placeholders) multiple times, which is great. However I've found you can't NEST them, so it doesn't actually solve my original problem.