Does res judicata preclude a cause of action for conspiracy that arises after a Complaint was filed, but prior to that initial claim's dismissal, if the new claims could have been introduced via supplement to an earlier pleading?

QUESTIONS PRESENTED UESTION #1: Does res judicata preclude a cause of action for conspiracy that arises after a Complaint was filed, but prior to that initial claim’s dismissal, if the new claims could have been introduced via supplement to an earlier pleading? UESTION #2: When a signatory’s provision of services has been interfered with by a stranger to the parties’ arbitration agreement, does this issue concern “the making of the arbitration agreement” as specified by 9 U.S.C. § 4 of the Federal Arbitration Act, such that the alleged conspiracy must be tried before the district court?