"They have to register their guests."

Translation: Ihre Gäste müssen sie registrieren.

[kwonnnn]

Can we flip the word order and say "Sie müssen registieren ihre Gäste"? Would that be correct too?

[Menschenkind]

That syntax is wrong. You might say 'Sie müssen ihre Gäste registrieren' though.

[kwonnnn]

Right, verb last, object second last. Thanks.

[Menschenkind]

That's not completely true anyway. You've got a compound verb here, which is 'registrieren müssen'. As far as I'm aware, it's subject, verb, object or o-s-v, if you want to stress the object. For my translation it's Subject, auxiliary verb, object, verb.

[lacow]

I like your translation more than the official one. It sounds less formal :)

[SimMoor]

Thats what I wrote and was marked as correct.