Adding one core to an existing core?

[Bruno Mannina]

Dear Users,

(Solr3.6 + Tomcat7)
I use since two years Solr with one core, I would like now to add one 
another core (a new database).

Can I do this without re-indexing my core1 ?
could you point me to a good tutorial to do that?

(my current database is around 200Go for 86 000 000 docs)
My new database will be little, around 1000 documents of 5ko each.

thanks a lot,
Bruno