What is the legal consequence when a defendant acknowledges the half-share claimed by one of two co-claimants of a property they supposedly jointly inherited or purchased?

Primary text

If two men claim ownership of a house based on a title that establishes co-ownership (e.g., 'We inherited it' or 'We bought it together'), and the defendant acknowledges half of it belongs to one claimant, the acknowledgment benefits both claimants because they both admitted the house was commonly owned. If a usurper seized half, that half is held against both, and the remainder is divided between them. If they did not claim joint ownership but each claimed a half-share individually, and the defendant acknowledged the share claimed by one, the other claimant is not joined, and the defendant must continue to defend against the other claimant's suit, as no joint ownership was admitted.