Multiple pages - Similar keywords

[Marvo]

I'm working on a site with a parent page and two minor pages all dealing with the primary/root keyword "log siding"  -  How do I optimize all three pages without bastardization of the primary keyword?

Parent page - keyword: half-log-siding and log-siding

Child Pages (linking from the parent)  cedar-log-siding  and Pine-log-siding.

They all feature "log-siding" and grade well for that keyword (as well as their own long-tail keywords), yet I think based on my rank tracking that Google is unhappy with the multiple pages all (seemingly focused) on log-siding.

Any ideas how I can effectively target all the long-tail keywords within their respective landing pages and not draw a penalty from Google towards my parent page and the root keyword?

Thanks,

Bill

[EGOL]

First... I am always an advocate of big content pages... 2000+ words and six great photos make me smile - and 3000 + nine photos is better.   So, I would be inclined to have cedar and pine and a few other species present on this single bigass page with photos... then if you can make another big article about each species I would do it... or a big photo gallery for each species.

Regarding the longtail..... you will get more longtail (in my opinion) with 2000 words on one page than you get from four pages with 500 words on each.  It will not happen immediately but check in a year.