No rules, but if your space is strongly committed to a particular style (and you like it that way), you may want to go easy on the eclectic approach. Some photos would help. Regarding furnishings from one "collection" (and this is just a personal opinion), beware of too much conformity unless you want to feel like you are living in a hotel. If you are interested in consulting a furniture designer for custom built pieces, I would be happy to discuss it further.

I would try hard NOT to match the pieces. Take a look at the photos for evidence. Actually, I seldom use end tables and when I do it's usually just one which does not match anything else. An end table is mostly good for just holding a lamp and I frequently use floor lamps.
Carolyn Albert-Kincl, ASID