It does actually make some sense... naam ka kya hai... Trilogy could've changed his name and and Appu could've been pregnant when she was thrown out of her sasural and told by her husband's family to hand them over their heir.... this would explain even better Appu's have for Anuyani: in her maternal home she and Sampu got everything they needed/wanted, except a husband/father: after learning of Vaman being a terrorist she may have forgiven Anuyani for writing her and Sampu of a male figure in their life, but she may still be angry about having had to give up her son.
And we know the Vermas were a family of criminals, so Trilok man have changed his surname but followed the family traditions.