To be a transferor of an item, you must be approved (via form 3) to possess the item and if approved, you should possess the item.
NFA, 26 U.S.C. Chapter 53, Section 479.84 The application, Form 4 (Firearms), shall be filed by the transferor and shall identify the firearm to be transferred by type; serial number; name and address of the manufacturer and importer, if known; model; caliber, gauge or size; in the case of a short-barreled shotgun or a short-barreled rifle, the length of the barrel; in the case of a weapon made from a rifle or shotgun, the overall length of the weapon and the length of the barrel; and any other identifying marks on the firearm.
Silencer Shop has a waiver to transfer, via Form 3, while concurrently transferring via Form 4. No waiver, not legal.
The short answer: No, not legally.