Keeping the day-to-day account at KBC and saving at Argenta is one of the most common setups in Belgium. It works fine, right up to the moment you want a single answer to "what do I actually have?" and end up adding two apps together in your head.
Yes. You connect each one once, on that bank’s own secure page, and both stay in sync from then on. There is no limit on how many of your banks can sit side by side.
No. Briliza recognises money moving between your own accounts as a transfer, so it is not counted as an expense on one side and income on the other. Your spending total stays honest.
Premium syncs all your connected banks, so it is the one for this. Plus syncs a single bank. Every plan lets you add further accounts by hand.