SEO Strategy for Microsite

[AmyLB]

I am working on a project to build a microsite of sorts that will represent a joint program between two large organizations with established web presences and strong domains. Each of the organizations has dedicated sections on their sites speaking to the program, but the leadership has decided the joint program deserves it's own site with dedicated content.

The two larger sites perform very well for SEO, and I don't necessarily want to jeopordize thir rankings by delivering content that competes directly with them. So I am doing some keyword research to find some opportunities that will alllow me to use the new site to target keywords not yet being captialized by the larger sites. My grand scheme is to have the three sites targeting the broadest array of keywords possible, thus maximizing exposure and avoiding competition.

Here is the rub: the content between the three sites will be different but very similar, and there will be plenty of cross linking, especially from the existing sites to the new site, as we grow the brand of the joint program.

I'm curious to here some expert opinions on what the puitfalls of the strategy are and what are some of the things I can do to avoid falling in the black hat category - I recognize that proliferating sites around a single topic and cross linking them is black hat. The organizations simply want to build a brand around a joint program and we are striggling to do that without a dedicated website.

[EGOL]

I would want the joint site to be the treasure of content.  Each of the organizations would write a unique press release suitable for their respective audiences, publish those releases on their main sites and link them to the microsite.    If this is a joint effort then they should not need a lot of ego thumping on their own sites.

[AmyLB]

Thanks. I understand the challene for future co