Section 5B. Subject to section 15 of chapter 184, an affidavit made by a person claiming to have personal knowledge of the facts therein stated and containing a certificate by an attorney at law that the facts stated in the affidavit are relevant to the title to certain land and will be of benefit and assistance in clarifying the chain of title may be filed for record and shall be recorded in the registry of deeds where the land or any part thereof lies.