NJM -
It likely won't "damage" anything... no... but you may find that they don't play nice together.
I had a somewhat related thing going on with some direct connections to part of my PV array, and it caused the classic (charge controller) MPPT algorithm to get confused and not load the panels properly. The end result of this was radically reduced overall system efficiency.
This isn't to say that *all* MPPT algos will get confused by interaction, as I was able to change to "legacy P&O" mode and counteract it somewhat. Ultimately tho, I disconnected the other load so that I could use the smarter algo for charging.
What you're facing there is what typically gets encountered with the so called "grown in place" phenomenon... normally encountered when the needs of the system demand more than available equipment in an existing nominal system voltage can provide. Battery voltage is one of those core system attributes that is part of defining the system itself. The dilemma of course is usually "well what do I do with all this extra equipment that's not compatible".
By all appearances, it looks like you're going in to all of this from scratch... My single piece of advice would be "simplify". If you're looking at loads that require things like inverters that need the 48V layout to be efficient, skip the 12 and 24 completely from the beginning.
Other than possibly a small auxiliary system that's more or less separate (or sometimes piggybacked after the main bank), the lower voltage stuff will just frustrate you down the road, and introduce extra points of failure. Neither of which are any good.
All that said, you might want to take a peek at
this to get a better feel for why all this matters so much. It was written with the idea of people in mind such as yourself that are heading into the magic of renewable, in hopes of saving you from some of the mistakes that lurk in the shadows that sneak up on newcomers.
Hope this helps, and welcome to the forum.
Steve