who occupied the premises on the date of the filing of the action may object to enforcement of the judgment against that occupant by filing a claim of right to possession as prescribed in this section. . . . Filing the claim of right to possession shall constitute a general appearance . . . .” (§ 1174.3, subd. (a), italics added.) If the court determines the claim of right to possession is valid, it shall “deem the unlawful detainer Summons and Complaint to be amended on their faces to include the claimant as defendant . . . .” (§ 1174.3, subd. (e)(2).) The complaint would then be served and defendant given an opportunity to respond. (Ibid.) The difference between Arrieta, supra,