I see what you mean. But your detailed intentions are not clear. I suppose the problem with what you are asking is that you might want to do many different things and each would have a slightly different solution.
It seems that you need a snippet on site one, that reads the content of site two, including all the children of a given page, and replicates it on site one. Of course the nature of your sites will play a factor in this, ie size and possible depths etc plus what you are actually trying to achieve with the data.
Now all the data you want is on the database of site two. Since you can read from any external table, you can read the table and pull the content of your first page, then run through a loop to collect all the first level children, then run again to get, if any, all the children of those pages etc etc as deep as you want it to go.
However I would not do this myself as it would involve too many database queries. As far as I know a single Etomite installation does not support multiple sites. Wordpress now does support multiple blogs for instance but the admin for it is a bit crappy and to be honest the multi site stuff is a bit limited. You can't just share data accross sites in a simple manner, you simply manage multiple blogs from one admin.
Can you give links to the two sites you want to link together, and some idea of where and how you want that data to appear?
Finally, a more simple approach might be to build a template that uses frames on both sites. Then one site could call a frame from the other site which might work and with careful design might appear totally seamless as well. (Although I would not use frames myself, there is no reason why you shouldn't use them. Google copes with frames quite easily.)
Hope that helps
PS Having reread all the above, I don't think the snippet I described would achieve a page by page replication that would work on both sites as you described. I think what you are asking is very complicated to achieve and I can't help wondering what you are trying to achieve. Look forward to the sample links to see what you mean in more detail.
PPS FINALLY! Just as a warning, if you do manage to replicate the content, one or both of the sites will be penalised by google for duplicated content. This could make the whole exercise very counter productive.
Edited by PaulD, 16 April 2010 - 08:56 PM.