And the terms in the statement of intent is that an agreement is determined through sufficient consensus, which is defined as a majority according to their parliamentary %.
I.e. ANC can't get to a majority without the DA (and vice versa) - this very definition is the reason why the DA almost didn't join the GNU, because the ANC changed the definition to suit them. Until they were forced to change it back at the last minute, because they didn't want Cyril being elected to a minority government and risk being MONC'd.
All these small parties were only included for optics, to keep SACP happy, which in the end didn't even matter with them contesting on their own. The statement of intent was drawn up by the ANC and DA, changes were only made based on their input because they were the only ones that mattered, not the irrelevant 1%ers. And there's nothing about 6/10 parties agreeing = agreement...