Thanks, I think I understand what you mean. However, the keyword in this case is zink, and however you use it - either in connection with aging or with the immune system, Google reads zinc on page 2 and on page 3, which is what you want. But I am still not sure how to avoid cannibalization. Do you mean that the keyword can appear on the contents of page 2 and page 3, but with a different context?
How would this apply to my case? My keyword is free games but i dont aim for page 2 or page 3 to be found with that keyword, I just want to use them so that page 1 is found better. Page 2 or page 3 would describe a different game each, so that the contents of page 2 and page 3 are totally differnt, but they contain the keyword free games. Eg page2 would say Skyrama is a free game in which you manage your own airport and would describe skyrama. Page 3 would say If you like free games about farms, then Farmerama is your game! Harvest vegetables... bla bla. Is this how you mean it?
