Yeah, not really sure what you're trying to do. vmsACARS doesn't download from Simbrief directly. Only a single simbrief gets stored by phpVMS - it's the "phpvms" format that's in the SB downloader. ACARS downloads that from your phpVMS directly, because they get deleted from the SB side pretty quickly.
A planned feature I have is that if you have ACARS open without a plan loaded, and you download the flightplan from the SB downloader, it will load the plan directly and try to find and load a bid, if it exists, from phpVMS automatically. But that'll be sometime in the future