I want to know if your system can help me out. I have 2 domains, co.uk and co.za. One hosted in South Africa and other in UK

The content is 95% the same but we want only some information (different due to country laws) to show on the uk and then have the some content from co.za to reflect on the co.uk. But we don't want to just link data in from co.za, the content must reflect as if the co.za content is on the co.uk. We have a problem with duplicated content

Hope I explain myself

The concept of JMS Multisites is based on using the same Joomla installation.
So you mentioned 2 differents hosting location.
Therefore you can not share the same Joomla PHP code as you have 2 servers.

Event if we could solve the "duplicated" Joomla installation, the "Article Sharing for JMS" need to access directly the DB of the other websites. It retreive the information from JMS Multisites that has the access to the DB of all the websites.

So in this particular case with different hosting, it should be verified that you can directly access the DB of the other hosting company directly. Somethime this is possible with some hosting company but this is not frequently the case.

So globally and by default, the answer is NO.
To do that with JMS Multisites, it could be perhaps possible if you install JMS Multisites in both hosting company and that you can have a direct access to the DB of the other hosting company. In this case, the idea would be to define in both hosting environement the same website to define the website of the other hosting company in a such way that the "Article Sharing for JMS" could be able to access directly the articles from the other websites.

This is not easy to setup and we did such very special settings with one customer with billable support.

If we have the content on the same server (DB) for the sites will it work, we want not to create duplicated content, we can host the uk in south africa

You can effectivelly save the two websites into the same DB or in different DB.
The key element is the place where the PHP code is located that must be on the same server. The DB themselve can be located on other servers as long as the HTTP Server has the access to these DB servers. This is the scenario used by many hosting companies that have the shared HTTP Server located on a server A and the DB server located on a set of DB server B, C, ...