I'm pretty much a beginner in German but I have a question about separable and inseparable verbs. I have read that there are verbs where the prefixes separate, others that don't and some, like those beginning with durch that sometimes separate. The inseparable version often being less literal and more figurative in meaning. In the German pop song Glück, they use the verb zusammenhalten. -Und Glück ist wie die Erde, die ales was air Sind, zusammenhält.-
When I look in the dictionary, it says that zusammenhalten separates, and that zusammen is a prefix that always separates. But of course I see here that it doesn't always separate. So can any separating verb stay unseparated when you conjugate it if you want to keep a more poetic sound?

Thanks in advance