Valid or invalid jurisdiction?

(1)In Ara district of Bihar,two persons 'A' and 'B' is having a joint 10 Acre ancestral Land.Both 'A' and 'B' are resident of Ara Dist of Bihar (2)In August 1964 ,'A' purchased a land of 2 kattha from third person in Rohtas dist of Bihar in favour of his name. (3)In september 1964,'A' puts a partition suit on whole property(10 Acre Ancestral Land + 2 kattha not ancestral land )in jurisdiction of Rohtas dist Court,so that 'B' cannot be aware of this partition case.'A' does some fraud in making wakalat naama from 'B' side.But actually 'B' did not appear in court of Rohtas.However The Rohtas court gives decree in favour of 'A' as ex-partie victory in sep,1964 itself. My question. Is 'A' allowed to make partition suit in Rohtas dist court. Th fact is Ara and Rohtas both are having different jurisdiction.? Note- 2 kothaa land was not of my ancestor in any way. 'A' purchased it from third unrelated person with a purpose of doing fraud partition in Rohtas court instead of Ara Dist Court. Can we challenge it in Ara court that Rohtaas Court is not a valid jurisdiction to decide partition on my ancestor Land ??.