I just finished reviewing my relationship chart with my boyfriend. I am not seeking specific advice on the configurations, so I will not post the chart here. Rather, I was thinking about the challenges of interpreting two charts between two people who have many different planetary influences (in their individual and relational chart).
Now, overall, our chart is pretty compatible in some core aspects. Trined suns, a trine between my sun and his moon, my Venus trine his sun, trined mars, my ascendent conjunct his sun, sextile moons.
But, we both have a very varied birth charts and thus, it is inevitable that positive planetary interactions in some aspects form conflicting planetary aspects with other planets. For example, his Mercury is Square my Mercury (me, Leo, him Scorpio) which also squares his sun! But, my Mercury trines his Venus, sextiles his Mars, and trines his Saturn. As Mercury is indicative of communication, it is interesting to see how this all manifests. He is pretty typical of a Scorpio in terms of the secretiveness in his communications and the underlying lack of trust thing. He implicitly states he trusts me, but it took a long while to build. Yet, he has a Sag Venus and I think my more vivacious and direct communication style actually turn him on. In our relationship, he struggles with being able to assert his needs directly (this is a overall pattern he has, he struggles with being able to ask for what he wants outright) yet he responds very well to me pointing this out and actually has almost immediately responded to any feedback I give him with positive change (I think the Mercury Trine Saturn is at play here with my communication style helping him to work on his problems with asserting his needs). Overall, we have highly productive communication once I bridge the subject, and communicate quite well. We have the skills to communicate, the tension comes from when we don't communicate.
And, that is just ONE example of how this works out. The reality is if you are a person with many different planetary influences, there is not a chart you can find with ANYONE that will not have inherent conflict even if your core planets configure well. If someone has planetary aspects trine/sextile/conjunct your venus/sun/moon they will ALSO square or oppose the other planets.
Another example....Mars Trine Mars, Jupiter, Sextile Venus, Sextile Saturn, Square Sun!
Another thing I believe is that possessing an element lacking in the others birth chart is a good balance for a relationship. My guy has a good blend of water, air, and fire....and only one earth influence in Pluto. But, the complementary aspects of balancing out each other different aspects is often overlooked in writings about relational astrology.
These are just my musing. I guess it comes down to a pretty basic point that can get overlooked in working with these types of charts. The more varied and complex the individual charts, the more challenging and complex it becomes to interpret the charts. And, the more basic rules of thumb can go right out the window.