Hello!
Has anyone ever tried a integration of a website into another (multi-site) installation?
Exists a extension, scripts or tutorials for such a todo?
I think for content tables there must be changed the uid´s and references during the import.
Thank you!
This came up just last week in slack (Slack):
Short version is: You should only do this if you know TYPO3 inside-out. I don’t think there are tutorials for this.
Quoting from there:
Good morning everyone.
The customer has 3 different TYPO3 installations and would like to combine the 3 sites in one > installation to reduce the update effort.
What is the best way to copy the content of 2 sites into another installation?
Would you use the import/export function?
Is it also possible to copy e.g. Powermail forms with the import/export function?
Or is there a better way?
Respondant 1: That is quite hard and error-prone. If they are the same TYPO3 version it might work. If it involves multi-languages and so on, you’re entering a world of pain.
Respondant 2: Can only agree with this. The only reason I see to put multiple sites into one instance is if they share the majority of a code base and structure.
It’s the same version and yes multilanguage.
i had the idea of export/import only one subpage at a time. It takes longer but you have better
control over possible errors etc.maybe i can write an own import with datahandler from
command line. I can export the content from the database (text, images) and then import the
content with datahandler. The 3 sites have 90% the same extensions, and the structure is also
90% the same.
But this goes only for “normal” sites without plugins etc.
Respondant 1: Personally I’ve achieved better results by manually copy+pasting results and assets… 
Thank you for your answer, I had already thought that and now I have to tell and learn this to my boss. In germany we would say “es gibt nicht die eierlegende Wollmilchsau” 