The last time I stayed at one of the private reserves, not in the KNP proper, but with the fences removed, the guide went to great length to explain that when the fences where removed agreements where signed covering issues for example - no hunting (maybe no commercial hunting), no introduction of new species, management of alien plants and rehabilitation.
I cannot conclusively rule out the existence of such agreements, but I've never heard of any. The fact that hunting is common and widespread supports the conclusion that no agreements exist as far as that's concerned.
New species (as in not indigenous to the area) is not really a problem. The Lowveld has a full complement of game, there is little (commercial) incentive to introduce alien species. There are certain fenced areas smack bang in the middle of the private reserves where species such as sable are bred. The population density may be unnaturally high in such localities, but the species as such are not new.
Sabi Sand have been known to chuck in 600-odd blue wildebeest every now and then to feed the lions.
God knows that the private reserves could do with an agreement (or even better, legislation) on management and rehabilitation. They generally do really badly in that respect. Some are nothing more than glorified zoos, with water holes and dams on every corner, rampant bush clearing to improve the view, etc.
None of the above supports the existence of agreements of any kind.
The example that was given was if an animal is injured, or sick, Sanparks has to be informed and appropriate action would be taken by Sanparks.
Definitely not. SANParks doesn’t do anything about sick or injured animals in its own national parks, they only intervene in the most exceptional cases. Private reserves do their own shooting, in certain cases a vet may be called in. If any official intervention is required, the provincial nature conservation or veterinary authorities will be called in.
In addition he indicated that Sanparks did carry out inspections.
Any inspections would be the responsibility of the relevant provincial authorities. These are seriously underfunded and under-resourced.