Content on multiple sites

Hi,
I have come accross some probelsm in what I thought straight forward and wondered if someone can point me in the right direction before go through many lines of thought to fix this problem (but may not work at all)..

Ok, I have 2 sites (www.reelgroove.com – main site and https://www.gregdorban.co.uk). I do not want to update info on both sites as it will be largerly similiar. So, I seek to log into reelgroove.com wordpress admin and when new posts (in certain catagories) are added, they automatically update gregdorban.co.uk.

I have played with the wp_rss func – however this only shows the title and not full post as desired. (and do not believe it to have this additional functionality, nor be able to format the title, post etc correctly even if could display all.)

I have thought about linking gregdorban to the same database (but do not really want to have to as on different domain).

So, to summarise, I seek post content in select catagorises to be shown in full on secondary site different domain (as seen on primary site). What are the ways achiving this?

THANKS!!!

Note: I will change the layout of gregdorban.co.uk once functionality is working correctly.