Upvote:3
In Germany there is a special kind of invitation called a VerpflichtungserklΓ€rung, where the sponsor guarantees to reimburse the German government for any costs should the visitor overstay. This kind of invitation is usually not required to apply for a visa, but it may cause the granting of a visa that would otherwise be denied (because the applicant is deemed a high risk for overstay). This letter must be filed with the municipal authorities, not the police.
But that wouldn't help with the Czech authorities.